minor #33115 [4.3] Update UPGRADE guide of 4.3 for EventDispatcher (alexislefebvre)
minor #33115 [4.3] Update UPGRADE guide of 4.3 for EventDispatcher (alexislefebvre)

This PR was merged into the 4.3 branch.

Discussion
----------

[4.3] Update UPGRADE guide of 4.3 for EventDispatcher

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | no
| License       | MIT
| Doc PR        | no

I updated `UPGRADE-4.3.md` to ease upgrading `EventDispatcher` to 4.3, related changes were introduced in https://github.com/symfony/symfony/pull/28920

This code is used in Symfony: https://github.com/symfony/symfony/blob/f8302262714674e3efbd775c9b107294d89fb77e/src/Symfony/Component/Security/Guard/GuardAuthenticatorHandler.php#L49

Thanks to @nicolas-grekas for the hint: https://github.com/symfony/symfony/commit/75369dabb8af73b0d0ad7f206d85c08cf39117f8#r34480203

Commits
-------

8b9b39d872 Update UPGRADE guide of 4.3 for EventDispatcher

nicolas-grekas/symfony,oleg-andreyev/symfony,bendavies/symfony,Slamdunk/symfony,ogizanagi/symfony,tgalopin/symfony,smatyas/symfony,nicolas-grekas/symfony,xabbuh/symfony,garak/symfony,hhamon/symfony,nicolas-grekas/symfony,pierredup/symfony,phramz/symfony,sgehrig/symfony,Tobion/symfony,Simperfit/symfony,lstrojny/symfony,d-ph/symfony,Tobion/symfony,derrabus/symfony,chalasr/symfony,xabbuh/symfony,phramz/symfony,damienalexandre/symfony,zorn-v/symfony,zerkms/symfony,ragboyjr/symfony,docteurklein/symfony,jakzal/symfony,tucksaun/symfony,MatTheCat/symfony,smatyas/symfony,xabbuh/symfony,romaricdrigon/symfony,ragboyjr/symfony,jderusse/symfony,mweimerskirch/symfony,jderusse/symfony,tgalopin/symfony,jvasseur/symfony,voronkovich/symfony,hhamon/symfony,paradajozsef/symfony,ro0NL/symfony,shieldo/symfony,docteurklein/symfony,lyrixx/symfony,zorn-v/symfony,alekitto/symfony,pyrech/symfony,hhamon/symfony,jvasseur/symfony,mweimerskirch/symfony,romaricdrigon/symfony,OskarStark/symfony,localheinz/symfony,phramz/symfony,zcodes/symfony,derrabus/symfony,dmaicher/symfony,jderusse/symfony,yceruto/symfony,mnapoli/symfony,paradajozsef/symfony,MatTheCat/symfony,Taluu/symfony,Tobion/symfony,ragboyjr/symfony,Koc/symfony,garak/symfony,alekitto/symfony,sgehrig/symfony,shieldo/symfony,hhamon/symfony,ogizanagi/symfony,1ed/symfony,HeahDude/symfony,romaricdrigon/symfony,pierredup/symfony,shieldo/symfony,Simperfit/symfony,bendavies/symfony,voronkovich/symfony,lstrojny/symfony,kbond/symfony,MatTheCat/symfony,mpdude/symfony,OskarStark/symfony,Nyholm/symfony,paradajozsef/symfony,jakzal/symfony,chalasr/symfony,derrabus/symfony,romaricdrigon/symfony,localheinz/symfony,jderusse/symfony,stof/symfony,localheinz/symfony,phramz/symfony,Slamdunk/symfony,zerkms/symfony,HeahDude/symfony,fabpot/symfony,smatyas/symfony,ogizanagi/symfony,HeahDude/symfony,smatyas/symfony,d-ph/symfony,Deamon/symfony,localheinz/symfony,kbond/symfony,Nyholm/symfony,mpdude/symfony,Deamon/symfony,voronkovich/symfony,HeahDude/symfony,mweimerskirch/symfony,1ed/symfony,bendavies/symfony,mnapoli/symfony,d-ph/symfony,nicolas-grekas/symfony,gonzalovilaseca/symfony,1ed/symfony,Deamon/symfony,dmaicher/symfony,Koc/symfony,yceruto/symfony,symfony/symfony,ro0NL/symfony,Simperfit/symfony,dmaicher/symfony,mweimerskirch/symfony,shieldo/symfony,Taluu/symfony,oleg-andreyev/symfony,zcodes/symfony,xabbuh/symfony,stof/symfony,symfony/symfony,fabpot/symfony,alekitto/symfony,ro0NL/symfony,mweimerskirch/symfony,alekitto/symfony,oleg-andreyev/symfony,lstrojny/symfony,Slamdunk/symfony,Taluu/symfony,Taluu/symfony,docteurklein/symfony,gonzalovilaseca/symfony,maidmaid/symfony,Simperfit/symfony,mnapoli/symfony,jvasseur/symfony,Deamon/symfony,d-ph/symfony,sgehrig/symfony,yceruto/symfony,zorn-v/symfony,kbond/symfony,tucksaun/symfony,ragboyjr/symfony,Simperfit/symfony,mpdude/symfony,tucksaun/symfony,dmaicher/symfony,derrabus/symfony,Deamon/symfony,tgalopin/symfony,docteurklein/symfony,zcodes/symfony,ogizanagi/symfony,jvasseur/symfony,Koc/symfony,maidmaid/symfony,smatyas/symfony,lyrixx/symfony,oleg-andreyev/symfony,ro0NL/symfony,gonzalovilaseca/symfony,symfony/symfony,maidmaid/symfony,curry684/symfony,jakzal/symfony,mnapoli/symfony,mnapoli/symfony,Slamdunk/symfony,pyrech/symfony,mpdude/symfony,yceruto/symfony,zcodes/symfony,damienalexandre/symfony,tucksaun/symfony,1ed/symfony,MatTheCat/symfony,garak/symfony,Tobion/symfony,pyrech/symfony,stof/symfony,curry684/symfony,jakzal/symfony,curry684/symfony,maidmaid/symfony,pyrech/symfony,lyrixx/symfony,pierredup/symfony,paradajozsef/symfony,chalasr/symfony,zerkms/symfony,voronkovich/symfony,sgehrig/symfony,Koc/symfony,curry684/symfony,pierredup/symfony,damienalexandre/symfony,garak/symfony,stof/symfony,lyrixx/symfony,fabpot/symfony,chalasr/symfony,tgalopin/symfony,OskarStark/symfony,kbond/symfony,docteurklein/symfony,bendavies/symfony,Nyholm/symfony,OskarStark/symfony,gonzalovilaseca/symfony,zorn-v/symfony,symfony/symfony,Nyholm/symfony,zerkms/symfony,damienalexandre/symfony,fabpot/symfony