build(deps): update rosell-dk/webp-convert requirement from ^1.1 to ^2.2

Updates the requirements on [rosell-dk/webp-convert](https://github.com/rosell-dk/webp-convert) to permit the latest version.
- [Release notes](https://github.com/rosell-dk/webp-convert/releases)
- [Commits](rosell-dk/webp-convert@1.1.0...2.2.1)

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

composer.json

@@ -17,7 +17,7 @@
         "php": ">=7.1",
         "ext-gd": "*",
         "ext-exif": "*",
-        "rosell-dk/webp-convert": "^1.1",
+        "rosell-dk/webp-convert": "^2.2",
         "symfony/config": "^3.3||^4.1",
         "symfony/dependency-injection": "^3.3||^4.1",
         "symfony/http-kernel": "^3.3||^4.1"