Become a CODEOWNER for typing (pythonGH-31374)

(cherry picked from commit 6f1efd1)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Author: JelleZijlstra

.github/CODEOWNERS

@@ -128,7 +128,7 @@ Lib/ast.py                    @isidentical
 
 **/*idlelib*                  @terryjreedy
 
-**/*typing*                   @gvanrossum @Fidget-Spinner
+**/*typing*                   @gvanrossum @Fidget-Spinner @JelleZijlstra
 
 **/*asyncore                  @giampaolo
 **/*asynchat                  @giampaolo