fix(annotation): use is instead of Is

Since the definition in the LEMS types is `is` too, and it's case
sensitive.

Author: sanjayankur31

pyneuroml/annotations.py

@@ -93,7 +93,7 @@ def __init__(self):
             "description": DC.description,
             "keywords": PRISM.keyword,
             "thumbnails": COLLEX.thumbnail,
-            "is_": BQBIOL.Is,
+            "is_": getattr(BQBIOL, "is"),
             "organisms": BQBIOL.hasTaxon,
             "encodes_other_biology": BQBIOL.encodes,
             "has_version": BQBIOL.hasVersion,