chore(package): update ol to version 6.3.1

Closes #349

Author: greenkeeper[bot]

package.json

@@ -54,7 +54,7 @@
     "http-server": "0.11.1",
     "jquery": "3.4.1",
     "mocha": "6.2.2",
-    "ol": "6.1.1",
+    "ol": "6.3.1",
     "phantomjs-prebuilt": "2.1.14",
     "selenium-webdriver": "3.6.0",
     "wait-on": "3.3.0"