Add back missing ruby deps (#6058)

Author: TimoPtr

Gemfile.lock

@@ -2,6 +2,9 @@ GEM
   remote: https://rubygems.org/
   specs:
     CFPropertyList (3.0.8)
+      base64
+      nkf
+      rexml
     abbrev (0.1.2)
     addressable (2.8.7)
       public_suffix (>= 2.0.2, < 7.0)
@@ -169,6 +172,7 @@ GEM
     mutex_m (0.3.0)
     nanaimo (0.4.0)
     naturally (2.3.0)
+    nkf (0.2.0)
     optparse (0.8.0)
     os (1.1.4)
     plist (3.7.2)