upgrade react-native-webview to 5.12.0 for demo

demo/package.json

     "react": "16.8.3",
     "react-native": "0.59.9",
     "react-native-autoheight-webview": "../",
-    "react-native-webview": "^5.11.0"
+    "react-native-webview": "^5.12.0"
   },
   "devDependencies": {
     "@babel/core": "^7.0.0",

demo/yarn.lock

   integrity sha1-W7weLSkUHJ+9/tRWND/ivEMKahY=
 
 react-native-autoheight-webview@../:
-  version "1.1.2"
+  version "1.1.3"
   dependencies:
     prop-types "^15.7.2"
 
-react-native-webview@^5.11.0:
-  version "5.11.0"
-  resolved "https://nexus.bybutter.com/repository/npm-group/react-native-webview/-/react-native-webview-5.11.0.tgz#7b1eeac7f3ea3a6f7bab3eefc10b272f0a008603"
-  integrity sha1-ex7qx/PqOm97qz7vwQsnLwoAhgM=
+react-native-webview@^5.12.0:
+  version "5.12.0"
+  resolved "https://nexus.bybutter.com/repository/npm-group/react-native-webview/-/react-native-webview-5.12.0.tgz#e673f72a287829444ddcbc7ea2f28f2e5862f9fb"
+  integrity sha1-5nP3Kih4KURN3Lx+ovKPLlhi+fs=
   dependencies:
     escape-string-regexp "1.0.5"
     invariant "2.2.4"