[atheris] Update to 3.0.* (#15141)

Author: srittau

stubs/atheris/METADATA.toml

@@ -1,10 +1,6 @@
-version = "2.3.*"
+version = "3.0.*"
 upstream_repository = "https://github.com/google/atheris"
 partial_stub = true
 
 [tool.stubtest]
 ignore_missing_stub = true
-# TODO (2025-03-05): unskip once `atheris` can be installed on `ubuntu-24.04`,
-# see https://github.com/python/typeshed/pull/13582 and
-# https://github.com/google/atheris/issues/82
-skip = true