fix(package): update firebase to version 7.9.1

Closes #19

Author: greenkeeper[bot]

package.json

@@ -16,7 +16,7 @@
     "@types/zeroclipboard": "2.0.31",
     "bootstrap": "4.4.1",
     "clipboard-polyfill": "2.8.6",
-    "firebase": "7.8.2",
+    "firebase": "7.9.1",
     "jquery": "3.4.1",
     "mustache": "4.0.0",
     "prop-types": "15.7.2",