Update README.md

Author: paraskevasleivadaros

README.md

@@ -9,4 +9,4 @@ UML Sequence Diagram: <br>
 ![Sequence Diagram](https://github.com/paraskevasleivadaros/SE-Exercise-3/blob/master/%CE%94%CE%B9%CE%AC%CE%B3%CF%81%CE%B1%CE%BC%CE%BC%CE%B1%20%CE%91%CE%BA%CE%BF%CE%BB%CE%BF%CF%85%CE%B8%CE%AF%CE%B1%CF%82%20%CF%84%CE%B7%CF%82%20%CE%9C%CE%B5%CE%B8%CF%8C%CE%B4%CE%BF%CF%85%20calculatePrice%20%CF%84%CE%B7%CF%82%20%CE%BA%CE%BB%CE%AC%CF%83%CE%B7%CF%82%20Ticket.png)
 
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