Change return type of `BootGodDb.Identify` to `IReadOnlyList`

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BootGodDB.cs

@@ -150,15 +150,15 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			} //end xmlreader loop
 		}
 
-		public static List<CartInfo> Identify(string sha1)
+		public static IReadOnlyList<CartInfo> Identify(string sha1)
 		{
 #if BIZHAWKBUILD_GAMEDB_ALWAYS_MISS
 			_ = sha1;
-			return new(capacity: 0);
+			return Array.Empty<CartInfo>();
 #else
 			if (acquire == null) throw new InvalidOperationException("Bootgod DB not initialized. It's a client responsibility because only a client knows where the database is located.");
 			acquire.WaitOne();
-			return instance._sha1Table.TryGetValue(sha1, out var l) ? l : new(capacity: 0);
+			return instance._sha1Table.TryGetValue(sha1, out var l) ? l : Array.Empty<CartInfo>();
 #endif
 		}
 	}

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.BoardSystem.cs

@@ -141,7 +141,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 		{
 			foreach (var hash in hash_sha1)
 			{
-				List<CartInfo> choices = BootGodDb.Identify(hash);
+				var choices = BootGodDb.Identify(hash);
 				//pick the first board for this hash arbitrarily. it probably doesn't make a difference
 				if (choices.Count != 0)
 					return choices[0];