Add Python 3.15 base64 and binascii updates (#15733) #5020

Job	Run time
Check scripts and tests with mypy (linux)	17s
Check scripts and tests with mypy (win32)	16s
Stubsabot dry run	30s
Check scripts and tests with pyright (Windows)	16s
Check scripts and tests with pyright (Linux)	19s
	1m 38s

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