Added 3x.ro free hosting service

3x.ro is a free hosting service in Romania, 

And with plenty of FP's out there in various blacklist projects

Signed-off-by: spirillen <44526987+spirillen@users.noreply.github.com>

PyFunceble/checker/availability/extras/rules.py

@@ -81,6 +81,7 @@ def __init__(self, status: Optional[AvailabilityCheckerStatus] = None) -> None:
                 (self.switch_to_down_if_status_code, {410, 424}),
             ],
             r"\.24\.eu$": [(self.switch_to_down_if_status_code, 503)],
+            r"\.3x\.ro$": [(self.switch_to_down_if_status_code, 404)],
             r"\.altervista\.org$": [(self.switch_to_down_if_status_code, 403)],
             r"\.angelfire\.com$": [(self.switch_to_down_if_status_code, 404)],
             r"\.blogspot\.": [self.handle_blogspot],