chore: add minimal workflow permissions (#70)

.github/workflows/build.yaml

@@ -15,13 +15,25 @@ on:
 
   workflow_dispatch:
 
+permissions:
+  actions: none
+  checks: none
+  contents: read
+  deployments: none
+  issues: none
+  packages: none
+  pull-requests: none
+  repository-projects: none
+  security-events: none
+  statuses: none
+
 jobs:
   # Quick checks, running linters, checking formatting, etc
   quick:
     runs-on: ubuntu-20.04
     steps:
       - name: Cancel previous runs
-        if: ${{ github.event_name == 'pull_request' }}
+        if: github.event_name == 'pull_request'
         uses: styfle/cancel-workflow-action@0.9.0
 
       - name: Checkout
@@ -49,7 +61,7 @@ jobs:
     name: images/${{ matrix.job}}
     steps:
       - name: Cancel previous runs
-        if: ${{ github.event_name == 'pull_request' }}
+        if: github.event_name == 'pull_request'
         uses: styfle/cancel-workflow-action@0.9.0
 
       - name: Checkout
@@ -61,14 +73,14 @@ jobs:
             --tag=${{ matrix.job }}
 
       - name: Authenticate to Docker Hub
-        if: ${{ github.event_name != 'pull_request' }}
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Push images to Docker Hub
-        if: ${{ github.event_name != 'pull_request' }}
+        if: github.event_name != 'pull_request'
         run: |
           ${{ github.workspace}}/scripts/push_images.sh \
             --tag=${{ matrix.job}}