Add top-level permissions block to satisfy workflow linter (#383)

.github/workflows/build-unified.yml

@@ -23,6 +23,9 @@ on:
 env:
   _AZ_REGISTRY: bitwardenprod.azurecr.io
 
+permissions:
+  contents: read
+
 jobs:
   build-docker:
     name: Build Docker image

.github/workflows/release-digital-ocean.yml

@@ -10,6 +10,9 @@ on:
 
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   build-image:
     name: Build Image

.github/workflows/release.yml

@@ -19,6 +19,9 @@ on:
 env:
   _AZ_REGISTRY: bitwardenprod.azurecr.io
 
+permissions:
+  contents: read
+
 jobs:
   setup:
     name: Setup