PYTHON-5391 Skip C extension build on GraalPy (#2349)

Co-authored-by: Steven Silvester <[email protected]>

Author: msimacek

_setup.py

@@ -130,7 +130,11 @@ def build_extension(self, ext):
     except ValueError:
         pass
     ext_modules = []
-elif sys.platform.startswith("java") or sys.platform == "cli" or "PyPy" in sys.version:
+elif (
+    sys.platform.startswith("java")
+    or sys.platform == "cli"
+    or sys.implementation.name in ("pypy", "graalpy")
+):
     sys.stdout.write(
         """
 *****************************************************\n