limiting permissions (#23)

* limiting permissions

* also adding concurrency

.github/workflows/tests.yaml

@@ -18,6 +18,26 @@ on:
     branches:
       - main
 
+permissions:
+  actions: none
+  attestations: none
+  checks: none
+  contents: read
+  deployments: none
+  id-token: none
+  issues: none
+  models: none
+  discussions: none
+  packages: none
+  pages: none
+  pull-requests: none
+  security-events: none
+  statuses: none
+
+concurrency:
+  group: '${{ github.workflow }}-${{ github.ref }}'
+  cancel-in-progress: true
+
 jobs:
   test-linux:
     strategy: