Potential fix for code scanning alert no. 10: Workflow does not contain permissions

GitHub was catching the lack of permission definitions as a CodeQL issue and suggested this change.

Looks sensible to me.

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: simonwgill

.github/workflows/test.yaml

@@ -2,6 +2,9 @@ name: Tests
 
 on: pull_request
 
+permissions:
+  contents: read
+
 jobs:
   typecheck:
     name: MyPy Check