Githubactions: Connect to localhost:80 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1] failed: Connection refused

Gitbub actions workflow for running tests throws an error org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:80/event/DEB-12345": Connect to localhost:80 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1] failed: Connection refused (Connection refused); nested exception is org.apache.http.conn.HttpHostConnectException: Connect to localhost:80 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1] failed: Connection refused (Connection refused) at

jobs:
  unit-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v1
      - uses: actions/cache@v2
        with:
          path: ~/.m2/repository
          key: ${{ runner.os }}-maven-unit-test-${{ hashFiles('**/pom.xml') }}
          restore-keys: |
            ${{ runner.os }}-maven-unit-test-
      - uses: actions/setup-java@v1
        with:
          java-version: 11
      - name: Run unit test
        run:
          mvn -s ${MAVEN_SETTINGS_FILE} clean test -U -Dspring.profiles.active=test
      - name: Create coverage report files
        run:
          mvn jacoco:report
      - name: Upload code coverage results
        uses: actions/upload-artifact@v2
        with:
          name: code-coverage-file
          path: target/site/jacoco/jacoco.xml

@ExtendWith(SpringExtension.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
@ActiveProfiles("test")
@Slf4j
public class CoreDbEventControllerITest {

    @Value("${server.port}")
    private int serverPort;
    private String orderNumber = "DEB-12345";

    @Test
    public void when_get_core_db_event_endpoint_is_called_then_http_response_is_returned_and_http_status_200(){
        var endpointUrl = String.format("http://localhost:%s/event/%s", 80, orderNumber);
        log.info("endpointurl : "+ endpointUrl);
        TestRestTemplate testRestTemplate = new TestRestTemplate();
        //Given
        ResponseEntity<CoreDbEventResponse> response = testRestTemplate.getForEntity(endpointUrl,
                                                                                CoreDbEventResponse.class);

        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
    }
}

Can someone help me how to map the port 80 to container port on Gitactions?