build(deps): bump mobx from 5.7.0 to 5.8.0 in /ui

Bumps [mobx](https://github.com/mobxjs/mobx) from 5.7.0 to 5.8.0.
- [Release notes](https://github.com/mobxjs/mobx/releases)
- [Changelog](https://github.com/mobxjs/mobx/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mobxjs/mobx/compare/5.7.0...5.8.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

ui/package.json

@@ -20,7 +20,7 @@
     "lodash.debounce": "4.0.8",
     "lodash.throttle": "4.1.1",
     "lodash.uniqueid": "4.0.1",
-    "mobx": "5.7.0",
+    "mobx": "5.8.0",
     "mobx-react": "5.4.3",
     "mobx-stored": "1.0.2",
     "moment": "2.22.2",

ui/yarn.lock

@@ -7374,10 +7374,10 @@ mobx-stored@1.0.2:
     lodash.merge "^4.6.1"
     traverse "^0.6.6"
 
-mobx@5.7.0:
-  version "5.7.0"
-  resolved "https://registry.yarnpkg.com/mobx/-/mobx-5.7.0.tgz#dc58cd02fbacc5346071c3e6563b6507aff71f59"
-  integrity sha512-i+EwjPLq/QSvOFtAuhcd5FFWDxWK3gCJCFbW5dhgc4wsaHB/cL6DEVms3vZDgc2txWcfzjYWfknjggE/c0c4fw==
+mobx@5.8.0:
+  version "5.8.0"
+  resolved "https://registry.yarnpkg.com/mobx/-/mobx-5.8.0.tgz#cf59eae4baa2fde4387ffb6462b7ccf3b497b03c"
+  integrity sha512-NsZB+9bF5j+nv9Qwk6bNeE3np26a4TbTGkMpOLf6o1zXoM9BtHPQn/00px4uZ2AXJXtQML5P4MEWdMm6icMIfQ==
 
 moment@2.22.2:
   version "2.22.2"