Bump plexapi from 4.7.2 to 4.8.0

Bumps [plexapi](https://github.com/pkkid/python-plexapi) from 4.7.2 to 4.8.0.
- [Release notes](https://github.com/pkkid/python-plexapi/releases)
- [Commits](https://github.com/pkkid/python-plexapi/compare/4.7.2...4.8.0)

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

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

requirements.txt

@@ -1,4 +1,4 @@
-PlexAPI==4.7.2
+PlexAPI==4.8.0
 tmdbv3api==1.7.6
 arrapi==1.2.3
 lxml==4.6.4