Maintenance: Bump koala from 3.0.0 to 3.1.0

Bumps [koala](https://github.com/arsduo/koala) from 3.0.0 to 3.1.0.
- [Release notes](https://github.com/arsduo/koala/releases)
- [Changelog](https://github.com/arsduo/koala/blob/master/changelog.md)
- [Commits](https://github.com/arsduo/koala/compare/v3.0.0...v3.1.0)

Gemfile.lock

@@ -302,10 +302,11 @@ GEM
     json (2.6.1)
     jwt (2.3.0)
     kgio (2.11.4)
-    koala (3.0.0)
+    koala (3.1.0)
       addressable
-      faraday
+      faraday (< 2)
       json (>= 1.8)
+      rexml
     libv8 (8.4.255.0)
     listen (3.7.0)
       rb-fsevent (~> 0.10, >= 0.10.3)