Update version_gem to version 1.1.6

Author: depfu[bot]

Gemfile.lock

@@ -159,7 +159,7 @@ GEM
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
     unicode-display_width (2.6.0)
-    version_gem (1.1.4)
+    version_gem (1.1.6)
     webrick (1.8.2)
     yaml (0.3.0)
     yard (0.9.37)