Added tests.

.gitlab-ci.yml

src/main/java/com/s3ai/entities/Ticket.java

src/test/java/com/s3ai/CinemaTests.java

src/test/java/com/s3ai/TestUtils.java

src/test/java/com/s3ai/entities/CinemaTest.java

src/test/java/com/s3ai/entities/TicketTest.java

src/test/java/com/s3ai/entities/UserTest.java

src/test/java/com/s3ai/services/CinemaServiceTest.java

src/test/java/com/s3ai/services/TicketServiceTest.java

src/test/java/com/s3ai/services/UserServiceTest.java

src/test/resources/cinemasFill.sql

src/test/resources/ticketsFill.sql

src/test/resources/usersFill.sql