[ENH]: Support using datetimes as positions argument to violin(...) #30417

import datetime

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
datetimes = [
    datetime.datetime(2023, 2, 10),
    datetime.datetime(2023, 5, 18),
    datetime.datetime(2023, 6, 6)
]
ax.violin(
    [
        {
            'coords': datetimes,
            'vals': [0.1, 0.5, 0.2],
            'mean': datetimes[1],
            'median': datetimes[1],
            'min': datetimes[0],
            'max': datetimes[-1],
            'quantiles': datetimes
        }
    ],
    positions=[datetime.datetime(2020, 1, 1)]
)

Traceback (most recent call last):
  File "/Users/dstansby/software/mpl/matplotlib/test.py", line 11, in <module>
    ax.violin(
  File "/Users/dstansby/miniforge3/envs/mpl-dev/lib/python3.12/site-packages/matplotlib/_api/deprecation.py", line 453, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dstansby/miniforge3/envs/mpl-dev/lib/python3.12/site-packages/matplotlib/axes/_axes.py", line 9064, in violin
    line_ends = [[-0.25 if side in ['both', 'low'] else 0],
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: unsupported operand type(s) for +: 'float' and 'datetime.datetime'