Build: Always use bundled soundtouch

Because we're disabling exceptions in it.

Might gain a bit of speed by -Ofast as well.

.github/workflows/scripts/linux/flatpak/modules/12-soundtouch.json

@@ -1,25 +0,0 @@
-{
-  "name": "soundtouch",
-  "buildsystem": "cmake-ninja",
-  "build-options": {
-    "strip": true
-  },
-  "sources": [
-    {
-      "type": "git",
-      "url": "https://codeberg.org/soundtouch/soundtouch.git",
-      "tag": "2.3.2",
-      "commit": "29fba832a7920a04eab956b3990c50e13d8c93f9"
-    }
-  ],
-  "cleanup": [
-    "/bin",
-    "/include",
-    "/lib/*.a",
-    "/lib/*.la",
-    "/lib/cmake",
-    "/lib/pkgconfig",
-    "/share/doc"
-  ]
-}
-