Bump apprise from 1.5.0 to 1.6.0

Bumps [apprise](https://github.com/caronc/apprise) from 1.5.0 to 1.6.0.
- [Release notes](https://github.com/caronc/apprise/releases)
- [Commits](https://github.com/caronc/apprise/compare/v1.5.0...v1.6.0)

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

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

requirements.txt

@@ -1,6 +1,6 @@
 --extra-index-url https://dl.cloudsmith.io/public/borgmatic-collective/borgmatic/python/simple/
 
-apprise==1.5.0
+apprise==1.6.0
 borgbackup==1.2.6
 borgmatic==1.8.3
 llfuse==1.5.0