Update symfony from 5.3 to 5.4

[xvilo]

Active support for Symfony 5.3 ended 6 days ago (01 Jan 2022). Symfony 5.4 was released 1 month and 1 week ago (29 Nov 2021) and it's support ends in 2 years and 10 months (30 Nov 2024).

[codecov[bot]]

Codecov Report

Merging #543 (a7dee37) into master (322570d) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #543   +/-   ##
=========================================
  Coverage     99.33%   99.33%           
  Complexity     1893     1893           
=========================================
  Files           301      301           
  Lines          5996     6013   +17     
=========================================
+ Hits           5956     5973   +17     
  Misses           40       40           

Impacted Files	Coverage Δ
src/Command/ClearMetadataCacheCommand.php	100.00% <100.00%> (ø)
src/Command/ProxySyncMetadataCommand.php	100.00% <100.00%> (ø)
src/Command/ProxySyncReleasesCommand.php	100.00% <100.00%> (ø)
src/Command/ScanAllPackagesCommand.php	100.00% <100.00%> (ø)
src/Command/SynchronizeAllPackagesCommand.php	100.00% <100.00%> (ø)
src/Command/SynchronizePackageCommand.php	100.00% <100.00%> (ø)
src/Command/UpdateAdvisoriesDbCommand.php	100.00% <100.00%> (ø)
src/Controller/Admin/ConfigController.php	100.00% <100.00%> (ø)
src/Controller/Admin/OrganizationController.php	100.00% <100.00%> (ø)
src/Controller/Admin/ProxyController.php	100.00% <100.00%> (ø)
... and 18 more

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[xvilo]

PHPUnit is ✅ was also able to do some stuff locally on my development machine. So I suspect this PR is fine 👍

[xvilo]

@akondas pushed the last change to address your comment, all should be fine now :)

[akondas]

Thanks @xvilo :beers: