only depend on readline package in CPython

shouldn't try to install it on PyPy

not sure about PyReadline on PyPy on Windows

setupbase.py

@@ -641,8 +641,8 @@ def get_bdist_wheel():
                 
                 for pkg in ("gnureadline", "pyreadline"):
                     _remove_startswith(requires, pkg)
-                requires.append("gnureadline; sys.platform == 'darwin'")
-                requires.append("pyreadline (>=2.0); sys.platform == 'win32'")
+                requires.append("gnureadline; sys.platform == 'darwin' and platform.python_implementation == 'CPython'")
+                requires.append("pyreadline (>=2.0); sys.platform == 'win32' and platform.python_implementation == 'CPython'")
                 for r in requires:
                     pkg_info['Requires-Dist'] = r
                 write_pkg_info(metadata_path, pkg_info)