Move NPM publishing to GH Actions and remove Travis

Author: mlarraz

.github/workflows/publish.yml

@@ -0,0 +1,21 @@
+name: Publish
+
+on:
+  release:
+    types:
+      - published
+
+jobs:
+  publish:
+    name: Publish to NPM Registry
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: 14
+          registry-url: 'https://registry.npmjs.org'
+      - run: yarn install
+      - run: yarn publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_AUTH_TOKEN }}