src/sage/dynamics/arithmetic_dynamics/projective_ds.py: add long time

Fix the CI warning,

  2025-07-14T18:34:32.9505595Z ##[warning]slow doctest:
  2025-07-14T18:34:32.9523476Z     f.Lattes_to_curve(check_lattes=true)
  2025-07-14T18:34:32.9525823Z Test ran for 16.48s cpu, 16.65s wall

by adding "# long time" to this test.

Author: orlitzky

src/sage/dynamics/arithmetic_dynamics/projective_ds.py

@@ -6972,7 +6972,7 @@ def Lattes_to_curve(self, return_conjugation=False, check_lattes=False):
             sage: P.<x,y>=ProjectiveSpace(QQbar, 1)
             sage: E=EllipticCurve([1, 2])
             sage: f=P.Lattes_map(E, 2)
-            sage: f.Lattes_to_curve(check_lattes=true)
+            sage: f.Lattes_to_curve(check_lattes=true)  # long time
             Elliptic Curve defined by y^2 = x^3 + x + 2 over Rational Field
 
         """