Auto merge of #12156 - jimberlage:12153/mime-type-s3, r=aneeshusa
Auto merge of #12156 - jimberlage:12153/mime-type-s3, r=aneeshusa

Adds explicit mime type to upload_nightly.sh

<!-- Please describe your changes on the following line: -->
This changes the script to pass the `--mime-type` option to `s3cmd`, as
described [here](http://s3tools.org/usage).  The MIME type used is
`application/octet-stream`.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #12153 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because this is a minimal change to the upload_nightly.sh script.

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thiagopnts/servo,ConnorGBrewster/servo,ConnorGBrewster/servo,canaltinova/servo,paulrouget/servo,pyfisch/servo,KiChjang/servo,larsbergstrom/servo,nrc/servo,saneyuki/servo,KiChjang/servo,peterjoel/servo,eddyb/servo,jimberlage/servo,avadacatavra/servo,splav/servo,peterjoel/servo,KiChjang/servo,sadmansk/servo,anthgur/servo,szeged/servo,rnestler/servo,dsandeephegde/servo,larsbergstrom/servo,nnethercote/servo,ConnorGBrewster/servo,emilio/servo,thiagopnts/servo,pyfisch/servo,KiChjang/servo,dsandeephegde/servo,SimonSapin/servo,mbrubeck/servo,mattnenterprise/servo,cbrewster/servo,larsbergstrom/servo,rnestler/servo,notriddle/servo,fiji-flo/servo,larsbergstrom/servo,rnestler/servo,eddyb/servo,DominoTree/servo,saneyuki/servo,SimonSapin/servo,canaltinova/servo,notriddle/servo,nrc/servo,sadmansk/servo,KiChjang/servo,splav/servo,pyfisch/servo,eddyb/servo,avadacatavra/servo,emilio/servo,larsbergstrom/servo,nrc/servo,thiagopnts/servo,nnethercote/servo,larsbergstrom/servo,jimberlage/servo,anthgur/servo,peterjoel/servo,saneyuki/servo,peterjoel/servo,notriddle/servo,SimonSapin/servo,nrc/servo,thiagopnts/servo,dsandeephegde/servo,CJ8664/servo,emilio/servo,splav/servo,mattnenterprise/servo,ConnorGBrewster/servo,CJ8664/servo,rnestler/servo,emilio/servo,saneyuki/servo,dati91/servo,peterjoel/servo,mattnenterprise/servo,sadmansk/servo,peterjoel/servo,ConnorGBrewster/servo,DominoTree/servo,upsuper/servo,splav/servo,dati91/servo,avadacatavra/servo,paulrouget/servo,anthgur/servo,fiji-flo/servo,pyfisch/servo,paulrouget/servo,mbrubeck/servo,peterjoel/servo,nnethercote/servo,SimonSapin/servo,paulrouget/servo,anthgur/servo,nnethercote/servo,cbrewster/servo,canaltinova/servo,mbrubeck/servo,nnethercote/servo,cbrewster/servo,eddyb/servo,mattnenterprise/servo,upsuper/servo,avadacatavra/servo,jimberlage/servo,DominoTree/servo,sadmansk/servo,paulrouget/servo,CJ8664/servo,pyfisch/servo,upsuper/servo,KiChjang/servo,szeged/servo,avadacatavra/servo,nnethercote/servo,DominoTree/servo,KiChjang/servo,larsbergstrom/servo,notriddle/servo,saneyuki/servo,szeged/servo,CJ8664/servo,szeged/servo,szeged/servo,szeged/servo,DominoTree/servo,peterjoel/servo,dati91/servo,dati91/servo,CJ8664/servo,emilio/servo,szeged/servo,fiji-flo/servo,avadacatavra/servo,notriddle/servo,jimberlage/servo,upsuper/servo,DominoTree/servo,mbrubeck/servo,splav/servo,emilio/servo,CJ8664/servo,fiji-flo/servo,splav/servo,sadmansk/servo,emilio/servo,thiagopnts/servo,dati91/servo,dati91/servo,fiji-flo/servo,nnethercote/servo,sadmansk/servo,canaltinova/servo,jimberlage/servo,upsuper/servo,notriddle/servo,thiagopnts/servo,upsuper/servo,ConnorGBrewster/servo,emilio/servo,saneyuki/servo,saneyuki/servo,dsandeephegde/servo,CJ8664/servo,splav/servo,saneyuki/servo,nrc/servo,fiji-flo/servo,canaltinova/servo,canaltinova/servo,cbrewster/servo,pyfisch/servo,anthgur/servo,pyfisch/servo,dati91/servo,anthgur/servo,fiji-flo/servo,splav/servo,nrc/servo,canaltinova/servo,eddyb/servo,paulrouget/servo,mbrubeck/servo,rnestler/servo,emilio/servo,szeged/servo,avadacatavra/servo,upsuper/servo,mbrubeck/servo,splav/servo,SimonSapin/servo,jimberlage/servo,cbrewster/servo,eddyb/servo,fiji-flo/servo,pyfisch/servo,nnethercote/servo,mattnenterprise/servo,jimberlage/servo,SimonSapin/servo,jimberlage/servo,dsandeephegde/servo,notriddle/servo,mattnenterprise/servo,notriddle/servo,SimonSapin/servo,cbrewster/servo,canaltinova/servo,pyfisch/servo,cbrewster/servo,CJ8664/servo,nrc/servo,peterjoel/servo,DominoTree/servo,cbrewster/servo,DominoTree/servo,paulrouget/servo,SimonSapin/servo,mattnenterprise/servo,jimberlage/servo,rnestler/servo,saneyuki/servo,thiagopnts/servo,paulrouget/servo,paulrouget/servo,dsandeephegde/servo,anthgur/servo,rnestler/servo,anthgur/servo,KiChjang/servo,DominoTree/servo,sadmansk/servo,thiagopnts/servo,notriddle/servo,DominoTree/servo,mbrubeck/servo,mbrubeck/servo,nnethercote/servo,nnethercote/servo,dsandeephegde/servo,szeged/servo,rnestler/servo,eddyb/servo,sadmansk/servo,ConnorGBrewster/servo,saneyuki/servo,eddyb/servo,paulrouget/servo,dsandeephegde/servo,szeged/servo,splav/servo,pyfisch/servo,mattnenterprise/servo,dati91/servo,notriddle/servo,peterjoel/servo,emilio/servo,larsbergstrom/servo,upsuper/servo,ConnorGBrewster/servo,larsbergstrom/servo,avadacatavra/servo,KiChjang/servo,larsbergstrom/servo,KiChjang/servo