Fix mapper + DTO

src/main/java/com/faf223/expensetrackerfaf/controller/auth/AuthenticationController.java

@@ -20,7 +20,7 @@ public class AuthenticationController {
     }
 
     @PostMapping("/authenticate")
-    public ResponseEntity<AuthenticationResponse> register(@RequestBody AuthenticationRequest request) {
+    public ResponseEntity<AuthenticationResponse> authenticate(@RequestBody AuthenticationRequest request) {
         return ResponseEntity.ok(service.authenticate(request));
     }
 }