Bump alabaster from 0.7.16 to 1.0.0 (pyca#11359)

Bumps [alabaster](https://github.com/sphinx-doc/alabaster) from 0.7.16 to 1.0.0.
- [Release notes](https://github.com/sphinx-doc/alabaster/releases)
- [Changelog](https://github.com/sphinx-doc/alabaster/blob/master/docs/changelog.rst)
- [Commits](sphinx-doc/alabaster@0.7.16...1.0.0)

---
updated-dependencies:
- dependency-name: alabaster
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

ci-constraints-requirements.txt

@@ -5,7 +5,7 @@
 # and then manually massaged to add version specifiers to packages whose
 # versions vary by Python version
 
-alabaster==0.7.16
+alabaster==1.0.0
     # via sphinx
 argcomplete==3.5.0; python_version >= "3.8"
     # via nox