CLDSRV-409: use latest s3cmd with python3

[williamlardier]

Fixes the CI, as python 2.7 is now removed from the action installing it. Instead of keeping old code, let's take advantage of the situation and upgrade everything.

This requires some minor updates in the test suite as the s3cmd output format changed a bit.

[bert-e]

Hello williamlardier,

My role is to assist you with the merge of this
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[williamlardier]

/force_reset

[bert-e]

Reset complete

I have successfully deleted this pull request's integration branches.

[bert-e]

Integration data created

I have created the integration data for the additional destination branches.

• this pull request will merge improvement/CLDSRV-409-fix-python-version into
  development/7.10
• w/7.70/improvement/CLDSRV-409-fix-python-version will be merged into development/7.70
• w/8.6/improvement/CLDSRV-409-fix-python-version will be merged into development/8.6
• w/8.7/improvement/CLDSRV-409-fix-python-version will be merged into development/8.7
• w/8.8/improvement/CLDSRV-409-fix-python-version will be merged into development/8.8

The following branches will NOT be impacted:

• development/7.4

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[bert-e]

Waiting for approval

The following approvals are needed before I can proceed with the merge:

• the author

• 2 peers

[williamlardier]

/approve

[bert-e]

In the queue

The changeset has received all authorizations and has been added to the
relevant queue(s). The queue(s) will be merged in the target development
branch(es) as soon as builds have passed.

The changeset will be merged in:

• ✔️ development/7.10

• ✔️ development/7.70

• ✔️ development/8.6

• ✔️ development/8.7

• ✔️ development/8.8

The following branches will NOT be impacted:

• development/7.4

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[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/7.10

• ✔️ development/7.70

• ✔️ development/8.6

• ✔️ development/8.7

• ✔️ development/8.8

The following branches have NOT changed:

• development/7.4

Please check the status of the associated issue CLDSRV-409.

Goodbye williamlardier.