Fix publishing (#160)

eng/pipelines/templates/build.yaml

@@ -9,7 +9,7 @@ steps:
       versionSpec: ${{ parameters.nodeVersion }}
     displayName: Install Node.js  ${{ parameters.nodeVersion }}
 
-  - script: npm install -g npm 
+  - script: npm install -g npm@6
     displayName: Install dependencies
 
   - script: npx @microsoft/rush update