Update default gems list at 67743d5823 [ci skip]

NEWS.md

@@ -49,7 +49,7 @@ The following default gems are updated.
 * optparse 0.4.0.pre.1
 * psych 5.1.0
 * reline 0.3.3
-* stringio 3.0.6
+* stringio 3.0.7
 * strscan 3.0.7
 * syntax_suggest 1.0.4
 * time 0.2.2