[Backport 12_5] Pythia Update to fix tau decays

[aandvalenzuela]

Backport of #8139, following #8147 (comment).

[cmsbuild]

A new Pull Request was created by @aandvalenzuela (Andrea Valenzuela) for branch IB/CMSSW_12_5_X/master.

@cmsbuild, @smuzaffar, @aandvalenzuela, @iarspider can you please review it and eventually sign? Thanks.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.
cms-bot commands are listed here

[aandvalenzuela]

please test with cms-externals/pythia8#29

[smuzaffar]

@aandvalenzuela , as cms-externals/pythia8#29 has been merged so no need explicitly test with https://github.com/cms-externals/pythia8/pull/29. A simple please test should be fine :-)

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-c2853d/28555/summary.html
COMMIT: 820a634
CMSSW: CMSSW_12_5_X_2022-10-26-2300/el8_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmsdist/8151/28555/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 13 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3697216
• DQMHistoTests: Total failures: 1003
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 3696190
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -0.004 KiB( 50 files compared)
• DQMHistoSizes: changed ( 312.0 ): -0.004 KiB MessageLogger/Warnings
• Checked 212 log files, 49 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[perrotta]

+1

• As decided during the ORP meeting of Oct 25
• It does not affect minbias production for PU samples
• It would be desirable for the Phase2 MC productions

[smuzaffar]

+externals

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next IB/CMSSW_12_5_X/master IBs (tests are also fine). This pull request will be automatically merged.