Update dependency lxml to >=5.3.0,<6.0.0 (#784)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

pyproject.toml

@@ -59,7 +59,7 @@ test = [
     "httpx~=0.27",
     "Jinja2~=3.1.2",
     "jsonschema~=4.23.0",
-    "lxml>=4.9.3,<5.3.0",
+    "lxml>=5.3.0,<6.0.0",
     "openai>=1.35,<1.41",
     "mock==5.1.*",
     "pre-commit<4",