[3.13] gh-111735: Skip turtle doctests when _tkinter is not available (GH-156417) (#156478)

(cherry picked from commit eb08902)

Author: StanFromIreland

Doc/library/turtle.rst

@@ -10,6 +10,7 @@
 **Source code:** :source:`Lib/turtle.py`
 
 .. testsetup:: default
+   :skipif: _tkinter is None
 
    from turtle import *
    turtle = Turtle()
@@ -473,6 +474,7 @@ Turtle motion
    turtle is headed.  Do not change the turtle's heading.
 
    .. doctest::
+      :skipif: _tkinter is None
       :hide:
 
       >>> turtle.goto(0, 0)
@@ -815,6 +817,7 @@ Turtle motion
    last *n* stamps.
 
    .. doctest::
+      :skipif: _tkinter is None
 
       >>> for i in range(8):
       ...     unused_stamp_id = turtle.stamp()
@@ -1349,8 +1352,11 @@ More drawing control
    font.  If *move* is true, the pen is moved to the bottom-right corner of the
    text.  By default, *move* is ``False``.
 
-   >>> turtle.write("Home = ", True, align="center")
-   >>> turtle.write((0,0), True)
+   .. doctest::
+      :skipif: _tkinter is None
+
+      >>> turtle.write("Home = ", True, align="center")
+      >>> turtle.write((0,0), True)
 
 
 Turtle state
@@ -1387,12 +1393,15 @@ Visibility
 
    Return ``True`` if the Turtle is shown, ``False`` if it's hidden.
 
-   >>> turtle.hideturtle()
-   >>> turtle.isvisible()
-   False
-   >>> turtle.showturtle()
-   >>> turtle.isvisible()
-   True
+   .. doctest::
+      :skipif: _tkinter is None
+
+      >>> turtle.hideturtle()
+      >>> turtle.isvisible()
+      False
+      >>> turtle.showturtle()
+      >>> turtle.isvisible()
+      True
 
 
 Appearance
@@ -1905,6 +1914,9 @@ Window control
    method, one can make visible those parts of a drawing which were outside the
    canvas before.
 
+   .. doctest::
+      :skipif: _tkinter is None
+
       >>> screen.screensize()
       (400, 300)
       >>> screen.screensize(2000,1500)