ci(release): use quoted shell expansion for RELEASE_VERSION

Replace ${{ env.RELEASE_TAG }} expression interpolation with quoted
shell variable expansion "$RELEASE_TAG" to prevent potential command
injection via the environment variable.

Co-authored-by: Claude <noreply@anthropic.com>

Author: wikkyk

.github/workflows/release.yml

@@ -26,7 +26,7 @@ jobs:
           go-version-file: go.mod
       - name: generate release artifacts
         run: |
-          make release-manifests RELEASE_VERSION=${{ env.RELEASE_TAG }}
+          make release-manifests "RELEASE_VERSION=$RELEASE_TAG"
       - name: generate release templates
         run: |
           make release-templates