Bump openpyxl from 3.1.4 to 3.1.5

Bumps [openpyxl](https://openpyxl.readthedocs.io) from 3.1.4 to 3.1.5.

---
updated-dependencies:
- dependency-name: openpyxl
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -33,7 +33,7 @@ PyGithub==1.58.2
 lxml==5.2.2
 Markdown==3.6
 mysqlclient==2.1.1
-openpyxl==3.1.4
+openpyxl==3.1.5
 Pillow==10.3.0  # required by django-imagekit
 psycopg2-binary==2.9.9
 cryptography==42.0.8