Add me to codeowners for hashlib & multiprocessing

I already effectively own these. (multiprocessing reluctantly, but I've
spent enough time in the code of late, it is important, and and
championing some changes, so I may as well be looped in there).

.github/CODEOWNERS

@@ -50,13 +50,13 @@ Objects/exceptions.c          @iritkatriel
 Python/traceback.c            @iritkatriel
 
 # Hashing
-**/*hashlib*                  @tiran
-**/*pyhash*                   @tiran
-**/*sha*                      @tiran
-**/*md5*                      @tiran
-**/*blake*                    @tiran
-/Modules/_blake2/**           @tiran
-/Modules/_sha3/**             @tiran
+**/*hashlib*                  @gpshead @tiran
+**/*pyhash*                   @gpshead @tiran
+**/sha*                       @gpshead @tiran
+Modules/md5*                  @gpshead @tiran
+**/*blake*                    @gpshead @tiran
+Modules/_blake2/**            @gpshead @tiran
+Modules/_hacl/**              @gpshead
 
 # logging
 **/*logging*                  @vsajip
@@ -120,6 +120,9 @@ Lib/ast.py                    @isidentical
 /Lib/unittest/mock.py         @cjw296
 /Lib/test/test_unittest/testmock/* @cjw296
 
+# multiprocessing
+**/*multiprocessing*          @gpshead
+
 # SQLite 3
 **/*sqlite*                   @berkerpeksag @erlend-aasland