add github workflow

Author: requestmethod

.github/workflows/npm-publish.yml

@@ -0,0 +1,15 @@
+- name: Get tag version
+  if: startsWith(github.ref, 'refs/tags/')
+  id: get_tag_version
+  run: echo ::set-output name=TAG_VERSION::${GITHUB_REF/refs\/tags\//}
+- uses: actions/setup-node@v2
+  with:
+    node-version: "18.x"
+    registry-url: "https://registry.npmjs.org"
+- name: npm build
+  run: deno run -A ./scripts/build.ts ${{steps.get_tag_version.outputs.TAG_VERSION}}
+- name: npm publish
+  if: startsWith(github.ref, 'refs/tags/')
+  env:
+    NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+  run: cd npm && npm publish