Make Seth the primary cpython3 oss-fuzz contact. (#12025)

@sethmlarson - Seth is the security developer in residence for CPython
at the PSF. He makes sense as the primary contact.

Stop using my former employers account as my oss-fuzz address given that
they kicked our team out for being too valuable.

projects/cpython3/project.yaml

@@ -1,10 +1,12 @@
 homepage: "https://python.org/"
 language: c++
-primary_contact: "gps@google.com"
+primary_contact: "seth@python.org"
 main_repo: "https://github.com/python/cpython"
 auto_ccs:
  - "alex.gaynor@gmail.com"
  - "ammar@ammaraskar.com"
+ - "greg@krypto.org"
+ - "pablogsal@python.org"
 fuzzing_engines:
   - afl
   - honggfuzz

projects/python3-libraries/project.yaml

@@ -3,7 +3,7 @@ main_repo: "https://github.com/python/cpython"
 language: c
 primary_contact: "guidovranken@gmail.com"
 auto_ccs:
- - "gps@google.com"
+ - "greg@krypto.org"
  - "alex.gaynor@gmail.com"
  - "ammar@ammaraskar.com"
  - "pablogsal@python.org"