Move types to devDependency

Author: samtstern

packages/geofire/package.json

@@ -38,13 +38,13 @@
     "package.json"
   ],
   "dependencies": {
-    "@firebase/database-types": "^0.6.0",
     "geofire-common": "5.1.0"
   },
   "peerDependencies": {
     "firebase": "^2.4.0 || 3.x.x || 4.x.x || 5.x.x || 6.x.x || 7.x.x"
   },
   "devDependencies": {
+    "@firebase/database-types": "^0.6.0",
     "@types/chai": "^4.1.7",
     "@types/mocha": "^5.2.5",
     "@types/node": "^10.12.21",