Bump syn from 2.0.90 to 2.0.91 in /src/_bcrypt #1495

Job	Run time
Python 3.8 on win32	3m 32s
Python 3.8 on macos-13	56s
pep8,packaging on linux, Rust stable	1m 30s
py312 on alpine	1m 0s
Python 3.13 on win32	2m 40s
Python 3.8 on macos-latest	1m 4s
mypy on linux, Rust stable	1m 11s
Python 3.8 on win64	2m 46s
py312 on alpine:aarch64	1m 16s
Python 3.13 on macos-13	56s
py38 on linux, Rust stable	42s
py312 on ubuntu-rolling:aarch64	58s
Python 3.13 on win64	3m 39s
Python 3.13 on macos-latest	34s
py39 on linux, Rust stable	1m 41s
py310 on linux, Rust stable	44s
py311 on linux, Rust stable	58s
py312 on linux, Rust stable	40s
py313 on linux, Rust stable	1m 3s
pypy3 on linux, Rust stable	1m 1s
pypy3 on linux, Rust stable	1m 30s
py313 on linux, Rust 1.64.0	1m 58s
py313 on linux, Rust beta	1m 21s
py313 on linux, Rust nightly	53s
all-green	2s
	34m 35s

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