Update sabre/dav requirement from ~4.5.0 to ~4.6.0

Updates the requirements on [sabre/dav](https://github.com/sabre-io/dav) to permit the latest version.
- [Release notes](https://github.com/sabre-io/dav/releases)
- [Changelog](https://github.com/sabre-io/dav/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sabre-io/dav/compare/4.5.0...4.6.0)

---
updated-dependencies:
- dependency-name: sabre/dav
  dependency-type: direct:production
...

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

composer.json

@@ -7,7 +7,7 @@
     "license" : "GPL-3.0-only",
     "require": {
         "php"           : "^7.2 || ^8.0",
-        "sabre/dav"     : "~4.5.0",
+        "sabre/dav"     : "~4.6.0",
         "twig/twig"     : "~2.14.8",
         "symfony/yaml"  : "^3.4",
         "psr/log"       : "^1",