Fix object has no attribute 'flush' when using without a console

[asomoza]

What does this PR do?

Fix a recurring problem when using diffusers without console, e.g. using pythonw.exe in windows, since there's no sys.stderr.

I can make a more advanced solution like using a FileHandler instead if there's no sys.stderr but don't know if it's worth the effort here. Users should implement their own error handling for this.

Fixes #3290

Who can review?

@sayakpaul @yiyixuxu @DN6

[HuggingFaceDocBuilderDev]

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[yiyixuxu]

thanks!