chore: Remove flake.lock and update update-flake-dependencies.yml as a test

Author: mrjones2014

.github/workflows/update-flake-dependencies.yml

@@ -2,6 +2,9 @@
 name: Update flake dependencies
 
 on:
+  # TODO this is just a test, remove the `push` trigger before merging
+  push:
+    branches: [ mrj/nix-flake-overlay ]
   schedule:
     - cron: '0 16 * * 5'
   workflow_dispatch: # for allowing manual triggers of the workflow