lib/micropython-lib: Update submodule for enum compatibility fixes.

Updates micropython-lib submodule to include enum package with fixes:
- Fix __import__() to use positional args (MicroPython compatibility)
- Fix IntFlag bitwise operations to use _value_ attribute directly
- Add Flag, IntFlag, StrEnum, auto(), and unique() support

These changes enable full enum functionality with the metaclass features
added in previous commits.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl