Fix: Resolve Unicode charmap error in stdout streaming

[victorchall]

The application would raise a UnicodeEncodeError ('charmap' codec can't encode character) when the caption_openai.py script printed a Unicode character.

This was caused by redirecting sys.stdout to a custom StreamingStdout object in app.py that was missing the encoding attribute. Python's print() function would then fall back to a default, non-Unicode-friendly system encoding.

The fix involves two changes to the StreamingStdout class:

1. Added self.encoding = 'utf-8' to the __init__ method to explicitly declare the stream's encoding.
2. Removed a now-redundant and incorrect block that attempted to decode bytes in the write method. This was related to a previous attempt at a fix and is no longer needed.