Update SoundTouch in Flatpak manifest (#671)

SoundTouch migrated to Codeberg from GitLab recently.
This updates the SoundTouch dependency in the Flatpak manifest.

Signed-off-by: TheEvilSkeleton <theevilskeleton@riseup.net>
Reference-to: https://github.com/tenacityteam/tenacity/pull/671

packaging/flatpak/org.tenacity.Tenacity.json

@@ -162,9 +162,9 @@
       "sources": [
         {
           "type": "git",
-          "url": "https://gitlab.com/soundtouch/soundtouch.git",
-          "tag": "2.3.0",
-          "commit": "c65afe49f697fcea87d9a134870c8d115d7700cc"
+          "url": "https://codeberg.org/soundtouch/soundtouch.git",
+          "tag": "2.3.1",
+          "commit": "e1f315f5358d9db5cee35a7a2886425489fcefe8"
         }
       ]
     },