chore(package): pass "*" option verbatim to prettier

Without quotes the shell will expand the glob, which is undesirable since it will pass unnecessary files to prettier

.travis.yml

@@ -23,7 +23,7 @@ jobs:
     - name: "Static analysis"
       script:
         - yarn lint
-        - yarn prettier --check --ignore-unknown *
+        - yarn prettier --check --ignore-unknown "*"
     - name: "Build demo site"
       script:
         - yarn demo:build