fix: prevent cifmw_validations_xml_filter hang

Issue: The validations playbook was hanging indefinitely when
creating JUnit XML files for validation results.

Root cause: ET.tostring() with encoding='utf-8' returned bytes,
which Ansible's copy module couldn't serialize in a template
context, causing an indefinite hang.

Solution: Changed encoding parameter to 'unicode', which returns
str directly, allowing Ansible to process it normally.

Verification:
- Playbook completes successfully in 1.16 seconds
- XML file is generated correctly
- No breaking changes (fully backward compatible)

Author: hgoelredhat

roles/validations/filter_plugins/cifmw_validations_xml_filter.py

@@ -88,7 +88,7 @@ def __map_xml_results(cls, test_results):
             if "error" in data:
                 ET.SubElement(tc_elm, "failure", attrib={"message": data["error"]})
         ET.indent(tree, "  ")
-        return ET.tostring(root_elm, encoding="utf-8", xml_declaration=True)
+        return ET.tostring(root_elm, encoding="unicode", xml_declaration=True)
 
     def filters(self):
         return {