avoid using hard-coded python version

[smuzaffar]

Avoid hard coded pythn verson. This should fix the DEVEL IB build errors where boost_python is looking for version 38 where as it should have been 39

[smuzaffar]

+externals

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next IB/CMSSW_12_0_X/master IBs after it passes the integration tests. This pull request will now be reviewed by the release team before it's merged. @silviodonato, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[cmsbuild]

A new Pull Request was created by @smuzaffar (Malik Shahzad Muzaffar) for branch IB/CMSSW_12_0_X/master.

can you please review it and eventually sign? Thanks.
@silviodonato, @dpiparo, @qliphy you are the release manager for this.
cms-bot commands are listed here

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-35c930/16588/summary.html
COMMIT: 3e22f3a
CMSSW: CMSSW_12_0_X_2021-07-07-2300/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmsdist/7115/16588/install.sh to create a dev area with all the needed externals and cmssw changes.

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:

• avoid using hard-coded python version #7115 @cms-sw: avoid using hard-coded python version
• Remove python deps from cmssw/fwlite #7114 @cms-sw: Remove python deps from cmssw/fwlite

You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-35c930/16588/git-recent-commits.json
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-35c930/16588/git-merge-result

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 5116 differences found in the comparisons
• DQMHistoTests: Total files compared: 38
• DQMHistoTests: Total histograms compared: 2786260
• DQMHistoTests: Total failures: 13
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2786225
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 37 files compared)
• Checked 160 log files, 37 edm output root files, 38 DQM output files
• TriggerResults: no differences found