Update import for H2StreamResetException

Motivation:

`H2StreamResetException` was moved in apple#1304, but used old location in apple#1307.
Those PRs were merged concurrently without updating the import.

Modifications:

- Update import for `H2StreamResetException` in `H2ResponseCancelTest`;

Result:

Build does not fail.

servicetalk-http-netty/src/test/java/io/servicetalk/http/netty/H2ResponseCancelTest.java

@@ -28,7 +28,7 @@
 import io.servicetalk.http.api.StreamingHttpResponse;
 import io.servicetalk.http.api.StreamingHttpResponseFactory;
 import io.servicetalk.http.api.StreamingHttpServiceFilter;
-import io.servicetalk.http.netty.H2ToStH1Utils.H2StreamResetException;
+import io.servicetalk.http.netty.Http2Exception.H2StreamResetException;
 import io.servicetalk.transport.api.TransportObserver;
 
 import org.junit.Test;