Bump xmlschema from 3.3.2 to 3.4.3 (#473)

Bumps [xmlschema](https://github.com/sissaschool/xmlschema) from 3.3.2 to 3.4.3.
- [Release notes](https://github.com/sissaschool/xmlschema/releases)
- [Changelog](https://github.com/sissaschool/xmlschema/blob/master/CHANGELOG.rst)
- [Commits](sissaschool/xmlschema@v3.3.2...v3.4.3)

---
updated-dependencies:
- dependency-name: xmlschema
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements/requirements_api.txt

@@ -26,5 +26,5 @@ mocpy==0.17.0
 healpy==1.18.0
 scipy==1.14.1
 pygcn==1.1.3
-xmlschema==3.3.2
+xmlschema==3.4.3
 lxml==5.3.0