refactor: modernized GenericRepository and UnitOfWork with newer code from Roma

Database/UnitOfWork/IUnitOfWork.cs

@@ -0,0 +1,16 @@
+
+namespace GamificationService.Database.UnitOfWork;
+
+public interface IUnitOfWork
+{
+    #region Repositories
+    #endregion
+
+    #region Methods
+    bool SaveChanges();
+    Task<bool> SaveChangesAsync();
+    Task BeginTransactionAsync();
+    Task CommitTransactionAsync();
+    Task RollbackTransactionAsync();
+    #endregion
+}