Update av requirement from ~=13.0.0 to ~=13.1.0

Updates the requirements on [av](https://github.com/PyAV-Org/PyAV) to permit the latest version.
- [Changelog](https://github.com/PyAV-Org/PyAV/blob/main/CHANGELOG.rst)
- [Commits](PyAV-Org/PyAV@v13.0.0...v13.1.0)

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

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

requirements.txt

@@ -1,7 +1,7 @@
 aiolimiter~=1.1.0
 anyio~=4.6.2.post1
 apngasm_python~=1.3.1
-av~=13.0.0
+av~=13.1.0
 beautifulsoup4~=4.12.3
 rookiepy~=0.5.6
 httpx~=0.27.2