fix: XAG -> XAH in alias_key.json, resolves #776

Author: corneliusroemer

pango_designation/alias_key.json

@@ -76,5 +76,5 @@
     "XAE": ["BA.2*","BA.1*"],
     "XAF": ["BA.1*","BA.2*"],
     "XAG": ["BA.1*","BA.2*"],
-    "XAG": ["BA.2*","BA.1*"]
+    "XAH": ["BA.2*","BA.1*"]
 }