Bump plexapi from 4.15.12 to 4.15.15

Bumps [plexapi](https://github.com/pkkid/python-plexapi) from 4.15.12 to 4.15.15.
- [Release notes](https://github.com/pkkid/python-plexapi/releases)
- [Commits](pkkid/python-plexapi@4.15.12...4.15.15)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -2,7 +2,7 @@ num2words==0.5.13
 numpy==1.26.4
 opencv-python==4.9.0.80
 pillow==10.3.0
-PlexAPI==4.15.12
+PlexAPI==4.15.15
 kometautils==0.3.4
 requests==2.31.0
 retrying==1.3.4