Don't use binary mode for cmdmod.exec_code

[lukasraska]

What does this PR do?

Fixes cmdmod.exec_code on Windows machines due to invalid file mode.

What issues does this PR fix or reference?

Fixes #34196

Previous Behavior

 The minion function caused an exception: Traceback (most recent call last):
      File "c:\salt\bin\lib\site-packages\salt\minion.py", line 1318, in _thread_return
        return_data = executor.execute()
      File "c:\salt\bin\lib\site-packages\salt\executors\direct_call.py", line 28, in execute
        return self.func(*self.args, **self.kwargs)
      File "c:\salt\bin\lib\site-packages\salt\modules\cmdmod.py", line 2296, in exec_code_all
        with salt.utils.fopen(codefile, 'w+t') as fp_:
      File "c:\salt\bin\lib\site-packages\salt\utils\__init__.py", line 1209, in fopen
        fhandle = open(*args, **kwargs)
    ValueError: Invalid mode ('w+tb')

New Behavior

Successfully executed

Tests written?

Not required