PHPSTAN and Rector updates + baseline update

[escopecz]

Q	A
Bug fix? (use the a.b branch)	[ ]
New feature/enhancement? (use the a.x branch)	[y]
Deprecations?	[ ]
BC breaks? (use the c.x branch)	[ ]
Automated tests included?	[ ]
Related user documentation PR URL	mautic/mautic-documentation#...
Related developer documentation PR URL	mautic/developer-documentation#...
Issue(s) addressed	Fixes #...

Description:

There should be more speed improvements for the new PHPSTAN and Rector versions. So pushing the update. Ya know, to save the planet.

Steps to test this PR:

1. Check that the build is green

[codecov]

Codecov Report

Merging #12531 (d7c9b16) into 5.x (4af87ed) will decrease coverage by 0.01%.
The diff coverage is n/a.

❗ Current head d7c9b16 differs from pull request most recent head fd7ebfb. Consider uploading reports for the commit fd7ebfb to get more accurate results

@@             Coverage Diff              @@
##                5.x   #12531      +/-   ##
============================================
- Coverage     57.27%   57.27%   -0.01%     
  Complexity    33529    33529              
============================================
  Files          2163     2163              
  Lines        101324   101324              
============================================
- Hits          58031    58030       -1     
- Misses        43293    43294       +1     

see 1 file with indirect coverage changes

[mabumusa1]

Changes looks good

[mollux]

@escopecz really cool! I saw the release of Rector, and saw the possibilities that it brings.

[mollux]

@escopecz @mabumusa1 This seems to be merged with a failing PHPSTAN tests, see the checks.
This impacts all current PR's against 5.x

[escopecz]

@mollux thanks for calling this out. Fixed in #12556

[mautibot]

This pull request has been mentioned on Mautic Forums. There might be relevant details there:

https://forum.mautic.org/t/announcing-mautic-5-beta-now-available-for-testing/29764/1