fix python 3.9+ incompatibility (#19)

* fix python 3.9+ incompatibility

#18

* python 3.9+

Co-authored-by: Alessio Fabiani <alessio.fabiani@geo-solutions.it>

Author: Guillaume Troupel

src/geoserver/layer.py

@@ -134,7 +134,7 @@ def resource(self):
         if self.dom is None:
             self.fetch()
         name = self.dom.find("resource/name").text
-        atom_link = [n for n in self.dom.find("resource").getchildren() if 'href' in n.attrib]
+        atom_link = [n for n in self.dom.find("resource") if 'href' in n.attrib]
         ws_name = workspace_from_url(atom_link[0].get('href'))
         if self.gs_version >= "2.13":
             if ":" in name:
@@ -158,7 +158,7 @@ def _resolve_style(self, element):
         else:
             style_name = element.find('name').text
             ws_name = None
-        atom_link = [n for n in element.getchildren() if 'href' in n.attrib]
+        atom_link = [n for n in element if 'href' in n.attrib]
         if atom_link and ws_name is None:
             ws_name = workspace_from_url(atom_link[0].get("href"))
         return self.catalog.get_styles(names=style_name, workspaces=ws_name)[0]