ci: fix bump-dashboard-version workflow

.github/workflows/bump-dashboard-version.yaml

@@ -36,6 +36,8 @@ jobs:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
 
       - name: Create PR to update dashboard version in Makefile
+        env:
+          GH_TOKEN: ${{ github.token }}
         run: |
           set -euxo pipefail
           git config --global user.name "${GITHUB_ACTOR}"
@@ -47,10 +49,10 @@ jobs:
 
           case "${EMQX_NAME}" in
             emqx)
-              sed -i "s|EMQX_DASHBOARD_VERSION=.*|EMQX_DASHBOARD_VERSION=${DASHBOARD_VERSION}|" Makefile
+              sed -i "s|EMQX_DASHBOARD_VERSION ?= .*|EMQX_DASHBOARD_VERSION ?= ${DASHBOARD_VERSION}|" Makefile
               ;;
             emqx-enterprise)
-              sed -i "s|EMQX_EE_DASHBOARD_VERSION=.*|EMQX_EE_DASHBOARD_VERSION=${DASHBOARD_VERSION}|" Makefile
+              sed -i "s|EMQX_EE_DASHBOARD_VERSION ?= .*|EMQX_EE_DASHBOARD_VERSION ?= ${DASHBOARD_VERSION}|" Makefile
               ;;
           esac
           git add Makefile