Update `add-to-output-repos.sh`
Update `add-to-output-repos.sh`

Specify the type of script in the file.

Before the change, if you run the script, you would get the error:

```sh
➜  ember-cli git:(release) ✗ ./dev/add-to-output-repos.sh
Failed to execute process './dev/add-to-output-repos.sh'. Reason:
exec: Exec format error
The file './dev/add-to-output-repos.sh' is marked as an executable but could not be run by the operating system.
```
kellyselden/ember-cli,thoov/ember-cli,buschtoens/ember-cli,kanongil/ember-cli,kanongil/ember-cli,twokul/ember-cli,sivakumar-kailasam/ember-cli,fpauser/ember-cli,gfvcastro/ember-cli,twokul/ember-cli,balinterdi/ember-cli,jgwhite/ember-cli,rtablada/ember-cli,asakusuma/ember-cli,akatov/ember-cli,raycohen/ember-cli,jrjohnson/ember-cli,pzuraq/ember-cli,akatov/ember-cli,mike-north/ember-cli,kategengler/ember-cli,elwayman02/ember-cli,thoov/ember-cli,Turbo87/ember-cli,pzuraq/ember-cli,patocallaghan/ember-cli,asakusuma/ember-cli,akatov/ember-cli,sivakumar-kailasam/ember-cli,HeroicEric/ember-cli,pzuraq/ember-cli,Turbo87/ember-cli,gfvcastro/ember-cli,kategengler/ember-cli,mike-north/ember-cli,cibernox/ember-cli,thoov/ember-cli,pzuraq/ember-cli,gfvcastro/ember-cli,thoov/ember-cli,cibernox/ember-cli,kellyselden/ember-cli,HeroicEric/ember-cli,ember-cli/ember-cli,mike-north/ember-cli,patocallaghan/ember-cli,Turbo87/ember-cli,jgwhite/ember-cli,jgwhite/ember-cli,ef4/ember-cli,balinterdi/ember-cli,fpauser/ember-cli,Turbo87/ember-cli,ef4/ember-cli,HeroicEric/ember-cli,rtablada/ember-cli,mike-north/ember-cli,twokul/ember-cli,rtablada/ember-cli,kanongil/ember-cli,buschtoens/ember-cli,fpauser/ember-cli,sivakumar-kailasam/ember-cli,elwayman02/ember-cli,cibernox/ember-cli,ef4/ember-cli,fpauser/ember-cli,rtablada/ember-cli,jgwhite/ember-cli,ember-cli/ember-cli,cibernox/ember-cli,kanongil/ember-cli,raycohen/ember-cli,gfvcastro/ember-cli,patocallaghan/ember-cli,ef4/ember-cli,twokul/ember-cli,patocallaghan/ember-cli,ember-cli/ember-cli,HeroicEric/ember-cli,kellyselden/ember-cli,kellyselden/ember-cli,jrjohnson/ember-cli,sivakumar-kailasam/ember-cli,akatov/ember-cli