test-webkitpy should not use assertion functions removed in python 3.12
Pull request: https://github.com/WebKit/WebKit/pull/17202
Pull request: https://github.com/WebKit/WebKit/pull/17241
Committed 267496@main (93f8745ec911): <https://commits.webkit.org/267496@main> Reviewed commits have been landed. Closing PR #17241 and removing active labels.
<rdar://problem/114761005>