Add permissions for GitHub actions

Author: mhalbritter

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

@@ -1,4 +1,6 @@
 name: Build and deploy
+permissions:
+  contents: read
 on:
   push:
     branches:

.github/workflows/build-on-windows.yml

@@ -1,4 +1,6 @@
 name: Build on Windows
+permissions:
+  contents: read
 on:
   push:
     branches:

.github/workflows/verification.yml

@@ -1,4 +1,6 @@
 name: Verification
+permissions:
+  contents: read
 on:
   schedule:
     - cron: '15 3 * * *'