Add package workflow

Include the necessary config opts in npmrc, package.json

.github/workflows/release-package.yml

@@ -0,0 +1,22 @@
+name: Node.js Package
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  publish-gpr:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+        with:
+          node-version: 12
+          registry-url: https://npm.pkg.github.com/
+      - run: npm ci
+      - run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{secrets.PACKAGE_TOKEN}}

.npmrc

@@ -0,0 +1 @@
+@srcery-colors:registry=https://npm.pkg.github.com/

package.json

@@ -3,6 +3,9 @@
   "version": "1.0.0",
   "main": "./srcery.js",
   "description": "Srcery palette exposed as a package, used in other projects",
+  "publishConfig": {
+    "@srcery-colors:registry": "https://npm.pkg.github.com"
+  },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },