forcing lock file on appveyor

Author: weaverryan

.appveyor.yml

@@ -11,11 +11,11 @@ platform:
 
 install:
   - ps: Install-Product node $env:nodejs_version $env:platform
-  - yarn
+  - 'yarn --frozen-lockfile'
 
 test_script:
   - node --version
   - yarn --version
   - yarn run test
 
-build: off
+build: off