ci: fix invalid way to retrieve branch name

Author: mkfsn

.github/workflows/draft-new-release.yaml

@@ -15,7 +15,7 @@ jobs:
       - name: Extract version from branch name
         if: startsWith(github.event.pull_request.head.ref, 'release/')
         run: |
-          BRANCH_NAME="${{ echo ${GITHUB_REF#refs/heads/} }}"
+          BRANCH_NAME=${GITHUB_REF#refs/heads/}
           VERSION=${BRANCH_NAME#release/}
           echo "RELEASE_VERSION=$VERSION" >> $GITHUB_ENV