adding check for v prefix for backward compatibility

Author: EvanDietzMorris

Common/biolink_utils.py

@@ -10,6 +10,8 @@
 
 def get_biolink_model_toolkit(biolink_version: str = None) -> Toolkit:
     version = biolink_version if biolink_version else BIOLINK_MODEL_VERSION
+    if not version.startswith("v"):
+        version = "v" + version
     schema_url = f"https://raw.githubusercontent.com/biolink/biolink-model/{version}/biolink-model.yaml"
     predicate_map_url = f"https://raw.githubusercontent.com/biolink/biolink-model/{version}/predicate_mapping.yaml"
     return Toolkit(schema=schema_url, predicate_map=predicate_map_url)