build-aux: Update Flatpak audio plugins branch

The KDE Runtime 6.6 relies on the Freedesktop SDK 23.08 and so the branch of audio plugins should be updated too.

build-aux/com.obsproject.Studio.json

@@ -32,7 +32,7 @@
         },
         "org.freedesktop.LinuxAudio.Plugins": {
             "directory": "extensions/Plugins",
-            "version": "22.08",
+            "version": "23.08",
             "add-ld-path": "lib",
             "merge-dirs": "vst",
             "subdirectories": true,