Fix for python 3.8

sia/context_template.py

@@ -1,3 +1,4 @@
+from bs4 import BeautifulSoup
 from typing import List, Dict
 import xml.etree.ElementTree as ET
 
@@ -12,8 +13,7 @@ def generate_context(containers: List[Dict[str, any]]) -> str:
     """
     context_elem = ET.Element("context")
     context_elem.append(format_containers_xml(containers))
-    ET.indent(context_elem, space="\t")
-    return ET.tostring(context_elem, encoding='unicode')
+    return BeautifulSoup(ET.tostring(context_elem, encoding='unicode'), "xml").prettify()
 
 def format_containers_xml(containers: List[Dict[str, any]]) -> ET.Element:
     """Format container statuses as XML string.