flatpak: Update librist library

The librist commit is what is used by obs-deps since
this commit https://github.com/obsproject/obs-deps/commit/06fdd5f.

CI/flatpak/com.obsproject.Studio.json

@@ -163,7 +163,7 @@
         {
           "type": "git",
           "url": "https://code.videolan.org/rist/librist.git",
-          "commit": "0b1aaf995c4cad83d562ec7887180cc6ee132c84"
+          "commit": "419f09ea9aa9bf15f9c43b7752ca878521543679"
         }
       ]
     },