Add permissions for contents in flaky tests workflow (#407)

Author: Stummi

.github/workflows/template_flaky_tests.yml

@@ -33,7 +33,8 @@ jobs:
   flaky-tests:
     name: Flaky-Tests
     runs-on: ubuntu-slim
-    permissions: {}
+    permissions:
+      contents: read
     steps:
       - name: Find flaky tests
         uses: Staffbase/github-action-find-flaky-tests@166ee4950d01688cea6a229e6c20ba28ce66c645 # v0.3.1