feature #42696 [Notifier] Mark Transport as final (fabpot)
feature #42696 [Notifier] Mark Transport as final (fabpot)

This PR was merged into the 5.4 branch.

Discussion
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[Notifier] Mark Transport as final

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | n/a <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | n/a

We've done the same for the Transport class of Mailer.

Commits
-------

3c38b5b037 [Notifier] Mark Transport as final

stof/symfony,d-ph/symfony,d-ph/symfony,HeahDude/symfony,hhamon/symfony,derrabus/symfony,derrabus/symfony,HeahDude/symfony,Tobion/symfony,xabbuh/symfony,ro0NL/symfony,Tobion/symfony,nicolas-grekas/symfony,HeahDude/symfony,xabbuh/symfony,stof/symfony,derrabus/symfony,mpdude/symfony,phramz/symfony,ogizanagi/symfony,symfony/symfony,ogizanagi/symfony,mpdude/symfony,paradajozsef/symfony,paradajozsef/symfony,derrabus/symfony,nicolas-grekas/symfony,curry684/symfony,phramz/symfony,sgehrig/symfony,Tobion/symfony,damienalexandre/symfony,oleg-andreyev/symfony,symfony/symfony,curry684/symfony,symfony/symfony,ogizanagi/symfony,damienalexandre/symfony,paradajozsef/symfony,tucksaun/symfony,symfony/symfony,sgehrig/symfony,stof/symfony,mpdude/symfony,tucksaun/symfony,damienalexandre/symfony,phramz/symfony,tucksaun/symfony,hhamon/symfony,phramz/symfony,hhamon/symfony,oleg-andreyev/symfony,ro0NL/symfony,xabbuh/symfony,hhamon/symfony,curry684/symfony,mpdude/symfony,stof/symfony,oleg-andreyev/symfony,d-ph/symfony,nicolas-grekas/symfony,xabbuh/symfony,tucksaun/symfony,oleg-andreyev/symfony,HeahDude/symfony,ogizanagi/symfony,nicolas-grekas/symfony,damienalexandre/symfony,paradajozsef/symfony,curry684/symfony,ro0NL/symfony,Tobion/symfony,sgehrig/symfony,ro0NL/symfony,sgehrig/symfony,d-ph/symfony