Fix tag parsing

Author: jniebuhr

.github/workflows/release.yml

@@ -10,7 +10,12 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
+      - name: Get tag
+        id: tag
+        uses: dawidd6/action-get-tag@v1
+
       - uses: docker/setup-buildx-action@v1
+
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v1
         with:
@@ -24,11 +29,11 @@ jobs:
           context: .
           tags: |
             ghcr.io/jniebuhr/aws-pca-issuer:latest
-            ghcr.io/jniebuhr/aws-pca-issuer:${{ github.event.release.tag_name }}
+            ghcr.io/jniebuhr/aws-pca-issuer:${{steps.tag.outputs.tag}}
           push: true
 
       - name: Publish Helm chart
         uses: stefanprodan/helm-gh-pages@master
         with:
           token: ${{ secrets.CR_PAT }}
-          app_version: ${{ github.event.release.tag_name }}
+          app_version: ${{steps.tag.outputs.tag}}