bpo-46355: Update pythoncapi_compat project URL (GH-31670)

Author: vstinner

Doc/whatsnew/3.11.rst

@@ -909,7 +909,7 @@ Porting to Python 3.11
       #endif
 
   Or use the `pythoncapi_compat project
-  <https://github.com/pythoncapi/pythoncapi_compat>`__ to get these two
+  <https://github.com/python/pythoncapi_compat>`__ to get these two
   functions on older Python versions.
 
 * Changes of the :c:type:`PyThreadState` structure members:
@@ -962,7 +962,7 @@ Porting to Python 3.11
       #endif
 
   Or use `the pythoncapi_compat project
-  <https://github.com/pythoncapi/pythoncapi_compat>`__ to get these functions
+  <https://github.com/python/pythoncapi_compat>`__ to get these functions
   on old Python functions.