Upgrade npm to get "ci"

script/vsts/platforms/linux.yml

@@ -13,6 +13,9 @@ phases:
       versionSpec: 8.9.3
     displayName: Install Node.js 8.9.3
 
+  - script: npm install --global npm@6.2.0
+    displayName: Update npm
+
   - script: |
       apt-get update
       apt-get install -y --no-install-recommends build-essential xvfb clang-3.5 fakeroot git libsecret-1-dev rpm libx11-dev libxkbfile-dev xz-utils xorriso zsync libxss1 libgconf2-4 libgtk-3-0

script/vsts/platforms/macos.yml

@@ -15,6 +15,9 @@ phases:
       versionSpec: 8.9.3
     displayName: Install Node.js 8.9.3
 
+  - script: npm install --global npm@6.2.0
+    displayName: Update npm
+
   - script: |
       if [ $IS_RELEASE_BRANCH == "true" ] || [ $IS_SIGNED_ZIP_BRANCH == "true" ]; then
         script/build --ci --code-sign --compress-artifacts

script/vsts/platforms/windows.yml

@@ -22,6 +22,12 @@ phases:
       versionSpec: 8.9.3
     displayName: Install Node.js 8.9.3
 
+  - script: |
+      ECHO Installing npm-windows-upgrade
+      npm install --global --production npm-windows-upgrade
+      ECHO Upgrading npm
+      npm-windows-upgrade --no-spinner --no-prompt --npm-version 6.2.0
+
   - script: |
       IF NOT EXIST C:\tmp MKDIR C:\tmp
       SET SQUIRREL_TEMP=C:\tmp