Remove get_rotation

Author: oscargus

lib/matplotlib/text.py

@@ -23,34 +23,6 @@
 _log = logging.getLogger(__name__)
 
 
-@_api.deprecated("3.6")
-def get_rotation(rotation):
-    """
-    Return *rotation* normalized to an angle between 0 and 360 degrees.
-
-    Parameters
-    ----------
-    rotation : float or {None, 'horizontal', 'vertical'}
-        Rotation angle in degrees. *None* and 'horizontal' equal 0,
-        'vertical' equals 90.
-
-    Returns
-    -------
-    float
-    """
-    try:
-        return float(rotation) % 360
-    except (ValueError, TypeError) as err:
-        if cbook._str_equal(rotation, 'horizontal') or rotation is None:
-            return 0.
-        elif cbook._str_equal(rotation, 'vertical'):
-            return 90.
-        else:
-            raise ValueError(f"rotation is {rotation!r}; expected either "
-                             "'horizontal', 'vertical', numeric value, or "
-                             "None") from err
-
-
 def _get_textbox(text, renderer):
     """
     Calculate the bounding box of the text.