chore: add permissions for example job in workflow files

Author: deandreamatias

.github/workflows/base-beta.yaml

@@ -28,6 +28,8 @@ jobs:
       enable-fix-tests: true
       fvm-flavor: beta
   example:
+    permissions:
+      contents: read
     uses: flutter-form-builder-ecosystem/.github/.github/workflows/build-examples.yaml@main
     with:
       fvm-flavor: beta

.github/workflows/base.yaml

@@ -26,6 +26,8 @@ jobs:
       codecov-name: flutter_form_builder
       enable-fix-tests: true
   example:
+    permissions:
+      contents: read
     uses: flutter-form-builder-ecosystem/.github/.github/workflows/build-examples.yaml@main