build(deps-dev): bump lxml from 6.0.0 to 6.1.0

Bumps [lxml](https://github.com/lxml/lxml) from 6.0.0 to 6.1.0.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-6.0.0...lxml-6.1.0)

---
updated-dependencies:
- dependency-name: lxml
  dependency-version: 6.1.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -18,7 +18,7 @@ dependencies = [
 # Install with `pip install pyxform[dev]`.
 dev = [
   "formencode==2.1.1",  # Compare XML
-  "lxml==6.0.0",        # XPath test expressions
+  "lxml==6.1.0",        # XPath test expressions
   "psutil==7.0.0",      # Process info for performance tests
   "ruff==0.12.4",        # Format and lint
 ]