Fixed issue where certian versions of Python don't recoginze dict as a type

Author: hsolbrig

linkml_runtime/utils/context_utils.py

@@ -50,7 +50,7 @@ def to_file_uri(fname: str) -> str:
         JsonObj(**{"@context": context_list[0] if len(context_list) == 1 else context_list})
 
 
-def map_import(importmap: dict[str, str], namespaces: Callable[[None], "Namespaces"], imp: Any) -> str:
+def map_import(importmap: Dict[str, str], namespaces: Callable[[None], "Namespaces"], imp: Any) -> str:
     sname = str(imp)
     if ':' in sname:
         prefix, lname = sname.split(':', 1)