Update bundled gems list at 2192f2e6bc [ci skip]

NEWS.md

@@ -546,7 +546,7 @@ Note: We're only listing outstanding class updates.
     * power_assert 2.0.3
     * test-unit 3.5.7
     * net-ftp 0.2.0
-    * net-imap 0.3.3
+    * net-imap 0.3.4
     * net-pop 0.1.2
     * net-smtp 0.3.3
     * rbs 2.8.2