Run "npm audit" for release branch too

I'd like to be notified about weird vulnerabilities in JavaScript
libraries for the release branch as well. It's double important
since the release branch ships particular pinned version of *all*
dependencies.

.github/workflows/release.yml

@@ -23,3 +23,10 @@ jobs:
         run: |
           cl.exe hello.c
           hello.exe
+  audit:
+    name: npm audit
+    runs-on: windows-latest
+    steps:
+      - name: Check out source code
+        uses: actions/checkout@v1
+      - run: npm audit