Potential fix for code scanning alert no. 1: Workflow does not contain permissions (#150)

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: nathan-gs

.github/workflows/showcase.yml

@@ -5,6 +5,9 @@ on:
     paths:
       - 'showcase/**'
 
+permissions:
+  contents: read
+
 jobs:
   validate-readmes:
     runs-on: ubuntu-latest