Update lxml requirement from <5.0 to <6.0

Updates the requirements on [lxml](https://github.com/lxml/lxml) to permit the latest version.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.9.3...lxml-5.1.0)

---
updated-dependencies:
- dependency-name: lxml
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.py

@@ -41,7 +41,7 @@
     include_package_data=True,
     install_requires=[
         "lxml>=4.9.3",
-        "lxml<5.0",
+        "lxml<6.0",
         "xmltodict>=0.13.0",
         "pandas>=2.0.0",
         "pandas<3.0.0",