treewide: remove wkennington as maintainer

He prefers to contribute to his own nixpkgs fork triton.
Since he is still marked as maintainer in many packages
this leaves the wrong impression he still maintains those.

pkgs/development/libraries/mbedtls/1.3.nix

@@ -29,6 +29,6 @@ stdenv.mkDerivation rec {
     description = "Portable cryptographic and SSL/TLS library, aka polarssl";
     license = licenses.gpl3;
     platforms = platforms.all;
-    maintainers = with maintainers; [ wkennington fpletz ];
+    maintainers = with maintainers; [ fpletz ];
   };
 }

pkgs/development/libraries/mbedtls/default.nix

@@ -34,6 +34,6 @@ stdenv.mkDerivation rec {
     description = "Portable cryptographic and TLS library, formerly known as PolarSSL";
     license = licenses.asl20;
     platforms = platforms.all;
-    maintainers = with maintainers; [ wkennington fpletz ];
+    maintainers = with maintainers; [ fpletz ];
   };
 }