Bump snowballstemmer from 1.2.1 to 2.2.0 in /docs

Bumps [snowballstemmer](https://github.com/snowballstem/snowball) from 1.2.1 to 2.2.0.
- [Changelog](https://github.com/snowballstem/snowball/blob/master/NEWS)
- [Commits](https://github.com/snowballstem/snowball/commits/v2.2.0)

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

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

docs/requirements.txt

@@ -11,7 +11,7 @@ Pygments==2.15.0
 pytz==2024.2
 requests==2.32.3
 six==1.11.0
-snowballstemmer==1.2.1
+snowballstemmer==2.2.0
 Sphinx==1.5.1
 sphinx-rtd-theme==0.1.9
 sphinxcontrib-phpdomain==0.12.0