minor #37595 Require PHPUnit 9.3 on PHP 8 (GrahamCampbell)
minor #37595 Require PHPUnit 9.3 on PHP 8 (GrahamCampbell)

This PR was squashed before being merged into the 4.4 branch.

Discussion
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Require PHPUnit 9.3 on PHP 8

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| License       | MIT

The first version of PHPUnit to support PHP 8.0 is PHPUnit 9.3.

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Depends on https://github.com/symfony/symfony/pull/37607. Related to https://github.com/composer/composer/pull/9054.

Commits
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54b13c04c9 Require PHPUnit 9.3 on PHP 8

xabbuh/symfony,Slamdunk/symfony,Slamdunk/symfony,tucksaun/symfony,fabpot/symfony,curry684/symfony,oleg-andreyev/symfony,symfony/symfony,paradajozsef/symfony,Tobion/symfony,mpdude/symfony,jderusse/symfony,phramz/symfony,Taluu/symfony,ogizanagi/symfony,tgalopin/symfony,d-ph/symfony,symfony/symfony,pierredup/symfony,HeahDude/symfony,mpdude/symfony,phramz/symfony,tucksaun/symfony,Nyholm/symfony,jderusse/symfony,jvasseur/symfony,ro0NL/symfony,mweimerskirch/symfony,damienalexandre/symfony,zerkms/symfony,Taluu/symfony,ro0NL/symfony,d-ph/symfony,derrabus/symfony,curry684/symfony,kbond/symfony,damienalexandre/symfony,Nyholm/symfony,hhamon/symfony,curry684/symfony,mweimerskirch/symfony,tgalopin/symfony,xabbuh/symfony,Deamon/symfony,hhamon/symfony,Slamdunk/symfony,jvasseur/symfony,Deamon/symfony,tgalopin/symfony,Nyholm/symfony,xabbuh/symfony,derrabus/symfony,phramz/symfony,mweimerskirch/symfony,zerkms/symfony,paradajozsef/symfony,MatTheCat/symfony,hhamon/symfony,oleg-andreyev/symfony,Deamon/symfony,ogizanagi/symfony,lyrixx/symfony,lyrixx/symfony,zerkms/symfony,HeahDude/symfony,stof/symfony,damienalexandre/symfony,kbond/symfony,OskarStark/symfony,zerkms/symfony,damienalexandre/symfony,stof/symfony,OskarStark/symfony,fabpot/symfony,symfony/symfony,sgehrig/symfony,ogizanagi/symfony,MatTheCat/symfony,Tobion/symfony,MatTheCat/symfony,sgehrig/symfony,jderusse/symfony,nicolas-grekas/symfony,Slamdunk/symfony,mpdude/symfony,mpdude/symfony,sgehrig/symfony,HeahDude/symfony,d-ph/symfony,Deamon/symfony,phramz/symfony,stof/symfony,Tobion/symfony,hhamon/symfony,paradajozsef/symfony,jderusse/symfony,lyrixx/symfony,pierredup/symfony,MatTheCat/symfony,mweimerskirch/symfony,Tobion/symfony,Deamon/symfony,kbond/symfony,nicolas-grekas/symfony,symfony/symfony,oleg-andreyev/symfony,fabpot/symfony,sgehrig/symfony,Nyholm/symfony,stof/symfony,fabpot/symfony,ogizanagi/symfony,lyrixx/symfony,jvasseur/symfony,d-ph/symfony,OskarStark/symfony,derrabus/symfony,tucksaun/symfony,ro0NL/symfony,nicolas-grekas/symfony,xabbuh/symfony,derrabus/symfony,HeahDude/symfony,tucksaun/symfony,ro0NL/symfony,oleg-andreyev/symfony,pierredup/symfony,OskarStark/symfony,paradajozsef/symfony,kbond/symfony,curry684/symfony,Taluu/symfony,jvasseur/symfony,pierredup/symfony,nicolas-grekas/symfony,tgalopin/symfony,mweimerskirch/symfony,Taluu/symfony