Use minimum required permissions for GitHub workflows

This reduces the attack surface if the workflows are ever compromised.

Co-Authored-By: triallax <[email protected]>
Co-Authored-By: RSoulwin <[email protected]>

Author: 3 people

.github/workflows/ci.yml

@@ -27,6 +27,9 @@ jobs:
   build-and-test-jvm:
     runs-on: ubuntu-latest
 
+    permissions:
+      contents: read
+
     steps:
       - uses: actions/checkout@v3
       - uses: gradle/wrapper-validation-action@v1