fix ui-release-trigger quoting issue

.github/workflows/ui-release-trigger.yml

@@ -16,5 +16,5 @@ jobs:
           TAG: ${{ github.event.release.tag_name }}
         run: |
           curl -u ${{ secrets.CIRCLE_TOKEN }}: -X POST --header "Content-Type: application/json" \
-          -d '{ "branch": "main", "parameters": {"TAG": "${TAG}" }}' \
+          -d '{ "branch": "main", "parameters": {"TAG": "'${TAG}'" }}' \
           https://circleci.com/api/v2/project/github/hashicorp/boundary-ui-releases/pipeline