Update beautifulsoup4 requirement

Updates the requirements on [beautifulsoup4](https://www.crummy.com/software/BeautifulSoup/bs4/) to permit the latest version.

---
updated-dependencies:
- dependency-name: beautifulsoup4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

tests/requirements.txt

@@ -1,5 +1,5 @@
 alabaster<=0.7.13
-beautifulsoup4<4.12.1,>=4.9.1
+beautifulsoup4>=4.9.1,<4.12.4
 coincidence>=0.2.0
 coverage>=5.1
 coverage-pyver-pragma>=0.2.1