Use correct Test annotation (java-native-access#297)

Motivation:

1a217e4 moved stuff over to junit5 but I missed one annotation

Modifications:

Use correct Test annotation and so switch to junit5 completely

Result:

Run all tests with junit5

src/test/java/io/netty/incubator/codec/quic/QuicTest.java

@@ -17,7 +17,7 @@
 
 import io.netty.channel.ChannelOption;
 import io.netty.util.AttributeKey;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.util.HashMap;
 import java.util.Map;