Add permissions section to workflows for content access

Signed-off-by: Adam Warner <me@adamwarner.co.uk>

Author: PromoFaux

.github/workflows/build-and-publish.yml

@@ -8,6 +8,9 @@ on:
   release:
     types: [published]
 
+permissions:
+  contents: read
+  packages: write
 
 env:
   dockerhub: ${{ secrets.DOCKERHUB_NAMESPACE }}/pihole

.github/workflows/build-and-test.yml

@@ -2,6 +2,9 @@ name: Build Image and Test
 on:
   pull_request:
 
+permissions:
+  contents: read
+
 jobs:
   build-and-test:
     runs-on: ${{ matrix.runner }}