Prepare 0.7.2 release

[garrison]

Remaining action items (checklist for patchlevel release):

• Test all tutorial notebooks on a hardware backend
• Update version [sub]string in all files where it appears in the repository
  • pyproject.toml
• move release notes to 0.7 directory
• merge everything except this PR on the 0.7.2 milestone
• double check that all recent PRs with stable backport potential have been backported.
• build docs locally; proofread the release notes
• merge this PR
• tag the release
  1. git checkout stable/0.7
  2. git pull
  3. git show (verify it's the commit we want to tag)
  4. git tag -a 0.7.2 -m "Circuit Knitting Toolbox 0.7.2"
  5. git show (double/triple check the tag is on the correct branch)
  6. git push origin 0.7.2
• Wait for CI to finish. The release should then be available on GitHub and pypi.
• get docs to deploy (should happen automatically at this point after CI runs both on stable/0.7 and then on the gh-pages branch)
• move remaining 0.7.2 milestone items to 0.7.3 milestone and close 0.7.2 milestone

Previous patchlevel release PR: #566

[coveralls]

Pull Request Test Coverage Report for Build 9100227439

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.468%

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Totals
Change from base Build 9100204408:	0.0%
Covered Lines:	3497
Relevant Lines:	3663

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💛 - Coveralls