Bump numpy from 1.21.6 to 1.22.0 in /docs

Bumps [numpy](https://github.com/numpy/numpy) from 1.21.6 to 1.22.0.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/RELEASE_WALKTHROUGH.rst)
- [Commits](numpy/numpy@v1.21.6...v1.22.0)

---
updated-dependencies:
- dependency-name: numpy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

docs/requirements.txt

@@ -16,7 +16,7 @@ importlib-metadata==4.11.4
 Jinja2==3.1.2
 MarkupSafe==2.1.1
 mpi4py==3.1.3
-numpy==1.21.6
+numpy==1.22.0
 packaging==22.0
 Pillow==9.4.0
 pip==22.3.1