Update default gems list at 8e426a3 [ci skip]

Author: matzbot

NEWS.md

@@ -160,7 +160,7 @@ The following default gems are updated.
 * io-console 0.8.1
 * io-nonblock 0.3.2
 * io-wait 0.3.2
-* json 2.13.1
+* json 2.13.2
 * optparse 0.7.0.dev.2
 * prism 1.4.0
 * psych 5.2.6