Fix deprecation warning: Replace java.util.Date with Instant in JWT creation

Co-authored-by: ebyhr <[email protected]>

Author: Copilot

gateway-ha/src/test/java/io/trino/gateway/ha/router/TestTrinoRequestUser.java

@@ -23,7 +23,6 @@
 
 import java.time.Instant;
 import java.util.Base64;
-import java.util.Date;
 import java.util.Optional;
 
 import static com.auth0.jwt.algorithms.Algorithm.HMAC256;
@@ -71,7 +70,7 @@ void testUserFromJwtToken()
         String token = JWT.create()
                 .withIssuer("gateway")
                 .withClaim(claimUserName, claimUserValue)
-                .withExpiresAt(Date.from(expiryTime))
+                .withExpiresAt(expiryTime)
                 .sign(algorithm);
 
         HttpServletRequest mockRequest = new QueryRequestMock()