Update beautifulsoup4 requirement from ~=4.12 to ~=4.13

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] <support@github.com>

app/site/requirements.txt

@@ -1,4 +1,4 @@
 -r ../requirements.txt
 
-Beautifulsoup4~=4.12
+Beautifulsoup4~=4.13
 lxml~=5.3