Drop the unneeded visual_novel_core dependency

ff_battle needs only the battle platform and the interface; depending on the content mod pulled the whole novel into every game that uses this core.

manifest.json

@@ -8,5 +8,5 @@
   "sources": [
     "src/**/*.cs"
   ],
-  "depends": [ "visual_novel_core>=1", "interface>=1", "turn_battle_base>=1" ]
+  "depends": [ "interface>=1", "turn_battle_base>=1" ]
 }