PY_SSIZE_T_MIN negate UB in unicode_format.c and bytesobject.c

[aisk]

Bug report

Bug description:

Original gist: https://gist.github.com/devdanzin/577421b083bad6802aa391b909d1a725

unicode_format_arg_parse (line 563): -PY_SSIZE_T_MIN is undefined behavior in C. Benign on two's-complement but technically UB. bytesobjects.c have the same problem.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-151847: Avoid undefined behaviour negating PY_SSIZE_T_MIN width in str/bytes formatting #151849