Bump to 3.13.0rc3 (#333)

Author: zanieb

pythonbuild/downloads.py

@@ -80,10 +80,10 @@
         "python_tag": "cp312",
     },
     "cpython-3.13": {
-        "url": "https://www.python.org/ftp/python/3.13.0/Python-3.13.0rc2.tar.xz",
-        "size": 21055084,
-        "sha256": "d60e8b7c10de4f71d2dffaf7c7be8efa54dc1e532fe931dbb84e5f625709e237",
-        "version": "3.13.0rc2",
+        "url": "https://www.python.org/ftp/python/3.13.0/Python-3.13.0rc3.tar.xz",
+        "size": 22527884,
+        "sha256": "c8bc790185af1cb77b75c01cbc1aa642dfdcf97a370d2d10090bc7baa70da57e",
+        "version": "3.13.0rc3",
         "licenses": ["Python-2.0", "CNRI-Python"],
         "license_file": "LICENSE.cpython.txt",
         "python_tag": "cp313",