ci: Specify default token permissions

bbhtt · bbhtt · commit b70debc0e98e · 2025-09-29T11:45:55.000+05:30
This reduces the permission of the default GitHub token to only the
one specified, we don't need anything else.
diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
@@ -12,6 +12,9 @@ env:
   DEBIAN_FRONTEND: noninteractive
   TESTS_TIMEOUT: 10 # in minutes
 
+permissions:
+  contents: read
+
 jobs:
   check-autotools:
     name: Build with gcc and test
