Skip uninstallable tags in QPY backwards compatibility tests (backport #13202)

[mergify]

Summary

When a tag has been made, but the package has not yet landed on PyPI, the QPY job fails in the environment-building step. This is not actually a failure of the QPY backwards-compatibility guarantees, and it isn't the job of the QPY tests to detect a bad tag anyway.

Details and comments

Since this commit is an acknowledgement that not every tag might be a valid version, and my editor was complaining about the safety of the various script calls, I made the variable expansion safe against word splitting, just in case.

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This is an automatic backport of pull request #13202 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 1344cdd has failed:

On branch mergify/bp/stable/0.46/pr-13202
Your branch is up to date with 'origin/stable/0.46'.

You are currently cherry-picking commit 1344cddbe.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .azure/lint_docs_qpy-linux.yml
	deleted:    test/qpy_compat/compare_versions.py
	new file:   test/qpy_compat/get_versions.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   test/qpy_compat/process_version.sh
	both modified:   test/qpy_compat/run_tests.sh

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[qiskit-bot]

Thank you for opening a new pull request.

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While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the following people are relevant to this code:

• @Qiskit/terra-core
• @mtreinish
• @nkanazawa1989

[coveralls]

Pull Request Test Coverage Report for Build 11027851929

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 87.236%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	4	93.13%

Totals
Change from base Build 10965672707:	0.01%
Covered Lines:	74555
Relevant Lines:	85464

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💛 - Coveralls

[ElePT]

LGTM