gh-143986: Modernize Lib/uuid.py: use f-strings

[tonghuaroot]

Description

Lib/uuid.py currently uses older string formatting methods (% operator and .format()) in a few places. This task resolves to modernizing these to use f-strings (PEP 498) for improved readability and consistency with modern Python codebases.

Proposed Changes

• Replace '%s(%r)' % (self.__class__.__name__, str(self)) with f'{self.__class__.__name__}({str(self)!r})' in UUID.__repr__.
• Replace os.fsencode('(%s)' % ip_addr) with os.fsencode(f'({ip_addr})') in _arp_getnode.
• Replace assert False, '_random_getnode() returned invalid value: {}'.format(_node) with f-string version in getnode.

Verification

• Run python Lib/test/test_uuid.py to ensure all tests pass.

• Issue: Modernize Lib/uuid.py: use f-strings #143986

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[bedevere-app]

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[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.