Add CI job for semantic release

.github/workflows/Publish.yml

@@ -0,0 +1,43 @@
+name: Publish
+on:
+  workflow_dispatch:
+  schedule:
+  - cron: '0 0 * * *'
+jobs:
+  release:
+    name: Packages
+    if: github.repository == 'MaxGraey/as-bignum'
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+      with:
+        ref: master
+    - uses: dcodeIO/setup-node-nvm@master
+      with:
+        node-version: current
+    - name: Install dependencies
+      run: |
+        npm -v
+        npm install
+    - name: Build packages
+      run: |
+        VERSION=$(npx aspublish --version)
+        if [[ "$VERSION" == "" ]]; then
+          echo "Changes do not trigger a release"
+        elif [[ "$VERSION" != "0."* ]]; then
+          echo "Unexpected version: $VERSION"
+          exit 1
+        else
+          echo "Building version: $VERSION"
+          npm version "$VERSION" --no-git-tag-version
+          npm run build
+          npm test
+        fi
+    - name: Publish packages
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      run: |
+        if [ $(node -pe "require('./package.json').version") != "0.0.0" ]; then
+          npx aspublish
+        fi