test: Fix query test failure for validator power

Author: s2quake

test/Libplanet.Explorer.Tests/GraphTypes/BlockTypeTest.cs

@@ -122,7 +122,7 @@ public async void Query()
                             { "blockHash", lastVotes[0].BlockHash.ToString() },
                             { "timestamp", new DateTimeOffsetGraphType().Serialize(lastVotes[0].Timestamp) },
                             { "validatorPublicKey", lastVotes[0].ValidatorPublicKey.ToString() },
-                            { "validatorPower", lastVotes[0].ValidatorPower },
+                            { "validatorPower", lastVotes[0].ValidatorPower?.ToString() },
                             { "flag", lastVotes[0].Flag.ToString() },
                             { "signature", ByteUtil.Hex(lastVotes[0].Signature) },
                         }

test/Libplanet.Explorer.Tests/GraphTypes/VoteTypeTest.cs

@@ -57,7 +57,7 @@ public async void Query()
             Assert.Equal(vote.BlockHash.ToString(), resultData["blockHash"]);
             Assert.Equal(new DateTimeOffsetGraphType().Serialize(vote.Timestamp), resultData["timestamp"]);
             Assert.Equal(vote.ValidatorPublicKey.ToString(), resultData["validatorPublicKey"]);
-            Assert.Equal(vote.ValidatorPower, resultData["validatorPower"]);
+            Assert.Equal(vote.ValidatorPower?.ToString(), resultData["validatorPower"]);
             Assert.Equal(vote.Flag.ToString(), resultData["flag"]);
             Assert.Equal(ByteUtil.Hex(vote.Signature), resultData["signature"]);
         }