Change to only run CI once on pull requests

Previously it would run twice, for no good reason.
This also adds running a weekly build. This may or may not be necessary,
but it's part of the new template module so we'll add it for consistency

Author: AlexanderWells-diamond

.github/workflows/code.yml

@@ -2,7 +2,15 @@ name: Code CI
 
 on:
   push:
+    branches:
+      - master
+      - main
+    tags:
+      - "*"
   pull_request:
+  schedule:
+    # Run every Monday at 8am
+    - cron: '0 8 * * MON'
 
 jobs:
   lint: