release tag set to openwrt-21.02

Author: pexcn

.github/workflows/build.yml

@@ -56,7 +56,7 @@ jobs:
         if: github.event_name == 'push'
         uses: ncipollo/release-action@v1
         with:
-          tag: openwrt-19.07
+          tag: openwrt-21.02
           allowUpdates: true
           artifacts: ${{ matrix.ARCH }}.tar.gz
           token: ${{ secrets.GITHUB_TOKEN }}