Allow partial identity updates

 
 
 @app.query
-def update_details(db, name, nickname, note, uid="/"):
+def update_details(db, name=None, nickname=None, note=None, uid="/"):
     """Update name of identity with given `uid`."""
     card = db.select(
         "identities",
         where="json_extract(identities.card, '$.uid[0]') = ?",
         vals=[uid],
     )[0]["card"]
-    card["name"] = [name]
-    card["nickname"] = [nickname]
-    card["note"] = [note]
+    if name:
+        card["name"] = [name]
+    if nickname:
+        card["nickname"] = [nickname]
+    if note:
+        card["note"] = [note]
     db.update(
         "identities",
         card=card,