Add granular permissions to GitHub action workflows

This commit adds granular permissions to the workflows that need them to
perform their tasks. The release action needs access to the "contents"
of a repo in order to create a release, and reusable-build-and-push
requires access to packages in order to publish the containers.

Author: Tehsmash

.github/workflows/main-merge.yml

@@ -4,6 +4,9 @@ on:
     branches:
       - main
 
+permissions:
+  packages: write
+
 jobs:
   build_and_push:
     uses: ./.github/workflows/reusable-build-and-push.yml

.github/workflows/release.yaml

@@ -4,6 +4,10 @@ on:
     tags:
       - "v[0-9]+.[0-9]+.[0-9]+"
 
+permissions:
+  packages: write
+  contents: write
+
 jobs:
   build_and_push:
     name: Build & Push