NEWS.md: remove a redundant bundled gems entry. [ci skip]

NEWS.md

@@ -23,10 +23,11 @@ Note: We're only listing outstanding class updates.
     * optparse 0.4.0.pre.1
     * stringio 3.0.5
     * strscan 3.0.6
+
 *   The following bundled gems are updated.
 
-    *minitest 5.17.0
-    *minitest 5.17.0
+    * minitest 5.17.0
+
 See GitHub releases like [GitHub Releases of Logger](https://github.com/ruby/logger/releases) or changelog for details of the default gems or bundled gems.
 
 ## Supported platforms