Skip broken HTML preview test case with libxml >= 2.14

[hardfalcon]

The test_no_tree test case is known to fail with libxml >= 2.14, so skip it for the time being when libxml >= 2.14 is used.

Reported-by: Ivan Shapovalov [email protected] Ref: https://gitlab.gnome.org/GNOME/libxml2/-/issues/908 Tested-by: Pascal Ernster [email protected] Closes: https://github.com/element-hq/synapse/issues/18406

[CLAassistant]

All committers have signed the CLA.

[anoadragon453]

Does the merge of https://github.com/element-hq/synapse/pull/18622 now obsolete this PR?

[hardfalcon]

Does the merge of #18622 now obsolete this PR?

Thanks, this solves the issue indeed, so I'll close this pull request.