Migrate Deployment CI to yarn

Author: fendor

.github/workflows/build.yml

@@ -11,19 +11,21 @@ jobs:
       - uses: actions/setup-node@v1
         with:
           node-version: 14
-      - run: npm ci
+      - run: yarn install --immutable --immutable-cache --check-cache
       - name: Publish to Visual Studio Marketplace
         id: publishToVSMarketplace
         uses: HaaLeo/publish-vscode-extension@v0
         with:
           pat: ${{ secrets.VS_MARKETPLACE_TOKEN }}
           registryUrl: https://marketplace.visualstudio.com
+          yarn: true
       - name: Publish to Open VSX Registry
         id: publishToOpenVSX
         continue-on-error: true
         uses: HaaLeo/publish-vscode-extension@v0
         with:
           pat: ${{ secrets.OPEN_VSX_TOKEN }}
+          yarn: true
       - name: Upload extension vsix to workflow artifacts
         uses: actions/upload-artifact@v2
         with: