Bump django from 3.2.15 to 3.2.18 in /docs (#30)

Bumps [django](https://github.com/django/django) from 3.2.15 to 3.2.18.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@3.2.15...3.2.18)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/requirements.txt

@@ -1,3 +1,3 @@
 Sphinx==4.4.0
-Django==3.2.15
+Django==3.2.18
 pyftpdlib==1.5.6