Generate release from tag

- Mimics kpack release process

Signed-off-by: Tom Kennedy <ktom@vmware.com>

Author: tomkennedy513

.github/actions/imgpkg-push/action.yml

@@ -27,7 +27,7 @@ runs:
   - name: Extract version
     shell: bash
     run: |
-      [[ $GITHUB_REF =~ ^refs\/heads\/release\/(.*)$ ]] && version=${BASH_REMATCH[1]} || version=${{ github.sha }}
+      [[ $GITHUB_REF =~ ^refs\/tags\/v(.*)$ ]] && version=${BASH_REMATCH[1]}  || version=${{ github.sha }}
       echo "VERSION=${version}" >> $GITHUB_ENV
 
   - name: Create version overlay

.github/workflows/ci.yaml

@@ -181,7 +181,7 @@ jobs:
       - bundle
       - webhook-image
       - setup-ca-certs-image
-    if: ${{ startsWith(github.ref, 'refs/heads/release/') }}
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
@@ -214,7 +214,7 @@ jobs:
     - name: Validate release version
       run: |
         echo "GITHUB_REF=${GITHUB_REF}"
-        [[ $GITHUB_REF =~ ^refs\/heads\/release\/(.*)$ ]] && version=${BASH_REMATCH[1]}
+        [[ $GITHUB_REF =~ ^refs\/tags\/v(.*)$ ]] && version=${BASH_REMATCH[1]}
         if [[ -z "${version}" ]]; then
           echo "ERROR: version not detected."
           exit 1