add release-insiders build

Publish a new `insiders` build everything a new commit gets pushed onto
the `master` branch.

.github/workflows/release-insiders.yml

@@ -0,0 +1,50 @@
+name: Release Insiders
+
+on:
+  push:
+    branches: [master]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [12]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+          registry-url: 'https://registry.npmjs.org'
+
+      - name: Use cached node_modules
+        id: cache
+        uses: actions/cache@v2
+        with:
+          path: node_modules
+          key: nodeModules-${{ hashFiles('**/package-lock.json') }}-${{ matrix.node-version }}
+          restore-keys: |
+            nodeModules-
+
+      - name: Install dependencies
+        if: steps.cache.outputs.cache-hit != 'true'
+        run: npm install
+        env:
+          CI: true
+
+      - name: Resolve version
+        id: vars
+        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+
+      - name: "Version based on commit: 0.0.0-insiders.${{ steps.vars.outputs.sha_short }}"
+        run: npm version 0.0.0-insiders.${{ steps.vars.outputs.sha_short }} --force --no-git-tag-version
+
+      - name: Publish
+        run: npm publish --tag insiders
+        env:
+          CI: true
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}