ci: Use least privilege principle for permissions

Declares only the required permissions per workflow.

Author: flovogt

.github/workflows/deploy-docs.yml

@@ -3,6 +3,10 @@ on:
   push:
     branches:
       - main
+
+permissions:
+  contents: write
+
 jobs:
   build-and-deploy:
     name: Build and Deploy

.github/workflows/github-ci.yml

@@ -8,6 +8,9 @@ on:
     branches:
       - main
 
+# No permissions are required for this workflow
+permissions: {}
+
 jobs:
   test:
     name: General checks and tests

.github/workflows/issues.yml

@@ -3,6 +3,9 @@ on:
   schedule:
     - cron: '00 20 * * *'
 
+permissions:
+  issues: write
+
 jobs:
   stale:
     name: Flag and close stale issues

.github/workflows/reuse-compliance.yml

@@ -8,6 +8,9 @@ on:
     branches:
       - main
 
+# No permissions are required for this workflow
+permissions: {}
+
 jobs:
   compliance-check:
     name: Compliance Check

.github/workflows/security-audit.yml

@@ -4,6 +4,10 @@ on:
   schedule:
     - cron: "36 4 * * *" # Run once a day
   workflow_dispatch:
+
+# No permissions are required for this workflow
+permissions: {}
+
 jobs:
   security-scan:
     name: Security Audit