tests/run-tests.py: Skip repl tests when running windows underneath.

Some versions of Python (for instance: the mingw-w64 version which can be
installed on MSYS2) do include a pty module and claim to be posix-like
(os.name == 'posix'), yet the select.select call used in run-tests.py hangs
forever.  To be on the safe side just exclude anything which might be
running on windows.

tests/run-tests.py

@@ -109,6 +109,10 @@ def run_micropython(pyb, args, test_file, is_special=False):
                         return b"SKIP\n"
                     import select
 
+                    # Even though these might have the pty module, it's unlikely to function.
+                    if sys.platform in ["win32", "msys", "cygwin"]:
+                        return b"SKIP\n"
+
                     def get(required=False):
                         rv = b""
                         while True: