Fix test harness casing and exclude test sources from app

GameList.Tests/VoteTests.cs

@@ -52,8 +52,9 @@ public class VoteTests
         vote.EnsureSuccessStatusCode();
 
         var mine = await player.GetFromJsonAsync<List<VoteRecord>>("/api/votes/mine");
+        Assert.NotNull(mine);
 
-        Assert.Equal(2, mine.Count);
+        Assert.Equal(2, mine!.Count);
         Assert.All(mine, v => Assert.Equal(9, v.Score));
     }