release version 8.1.8

[AndreasBackx]

• Decide to make a release.
• Ensure the change log has entries for each user-facing non-docs change, with links to the related issue reports.
• Ensure each issue and PR is in the milestone.
• Create a release-A.B.C branch.
• Change "Unreleased" to "Released YYYY-MM-DD" in CHANGES.md.
• Remove the ".dev" suffix from the version in pyproject.toml.
  • There is no version in pyproject.toml so I changed __version__ in the code as that was the only reference with the version it seems.
• Commit git commit -am 'release version A.B.C' and create a PR.
• Tag git tag -am 'release version A.B.C' A.B.C and push git push origin A.B.C.
  • I am blocked here. I do not have the rights to push tags.
• Watch the tests pass and build jobs begin.
• Edit the generated draft release page with our standard message template.
• Approve the upload job.
• Merge the PR. Use "create a merge commit", not "squash" or "rebase"!
• Close the milestone.
• Publish the draft release page.
• Start the next version(s), creating a change log section, bumping the version in pyproject.toml with the .dev suffix.
• Done!

Resolves #2793.