chore: Prepare release 2.18.0 #6048

Job	Run time
mypy	1m 11s
Test Minimal Pydantic 1 application	29s
pyright	1m 2s
Test server integration (uvicorn<0.27.0)	56s
test_typing_extensions (4.13.1)	47s
Test Minimal Application with Base Dependencies	20s
validate	52s
Test server integration (uvicorn>=0.27.0)	52s
test_typing_extensions (4.12.1)	51s
slotscheck	26s
test_typing_extensions (latest)	50s
test (3.13) / test	2m 38s
test (3.11) / test	1m 54s
test (3.12) / test	3m 17s
test (3.8) / test	3m 10s
test (3.10) / test	2m 14s
test (3.9) / test	2m 1s
test-platform-compat	-5s
build-docs	0s
upload-test-coverage	24s
test_success	4s
codeql	-1s
	24m 12s

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