Synapse doesn't detect URL preview dependencies if built with poetry-core 1.3.0, raising runtime errors

[DMRobertson]

This is causing CI failures:

Synapse 1.69.0rc1 does not provide the feature 'url_preview'

even though the requisite dependencies are installed. The problem is that python-poetry/poetry-core#476 now enforces https://peps.python.org/pep-0685/#specification. Wheels built by poetry-core include metadata describing an extra url-preview with a - but NOT url_preview with an _. This means the dependency-checking code in Synapse here

synapse/synapse/config/repository.py

Lines 206 to 208 in 7b67e93

	self.url_preview_enabled = config.get("url_preview_enabled", False)
	if self.url_preview_enabled:
	check_requirements("url_preview")

will fail.

People who've also installed from source after the release of poetry-core 1.3.0 are going to be seeing this.

Assuming we want to be able to use future poetry-core releases, we'll need to update the dependency-checking code to account for this.

[DMRobertson]

#14080 should avoid the problem by pinning the build-system requirements. Leaving this issue open though in case we do want to use newer versions of poetry-core in the future.