Fix netconf module_utils dict changed size issue (#46778)

Fixes #46755

Use list() to copy the keys of attribute dict
while iterating over attribute dict.

(cherry picked from commit 58aaf53271)

Update Changelog

changelogs/fragments/netconf_module_utils_py3_fix.yaml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+- netconf_config - Fix netconf module_utils dict changed size issue (https://github.com/ansible/ansible/pull/46778)

lib/ansible/module_utils/network/netconf/netconf.py

@@ -131,7 +131,7 @@ def sanitize_xml(data):
         # remove attributes
         attribute = element.attrib
         if attribute:
-            for key in attribute:
+            for key in list(attribute):
                 if key not in IGNORE_XML_ATTRIBUTE:
                     attribute.pop(key)
     return to_text(tostring(tree), errors='surrogate_then_replace').strip()