Update version_gem to version 1.1.8

Author: depfu[bot]

Gemfile.lock

@@ -166,7 +166,7 @@ GEM
     unicode-display_width (3.1.4)
       unicode-emoji (~> 4.0, >= 4.0.4)
     unicode-emoji (4.0.4)
-    version_gem (1.1.7)
+    version_gem (1.1.8)
     webrick (1.8.2)
     yaml (0.3.0)
     yard (0.9.37)