Set labels to data using plot_altitude

I want to make a simple plot that shows the evolution of altitude with time for different declinations

The working code snippet without labels is the following,

```python
fig, ax = plt.subplots()

for dec in range(-90,90,10):

test_source = SkyCoord(dec=dec, ra=22,unit="deg",frame="icrs")

time_range = Time([f"2023-01-01 00:00", f"2023-01-01 23:59"])
time_resolution = 1 * u.h
observe_time = time_grid_from_range(time_range, time_resolution=time_resolution)

plot_options = {#"label":dec,
"fmt":"-"
}

plot_altitude(test_source,
observer,
observe_time,
ax=ax,
airmass_yaxis=True,
style_kwargs=plot_options
)
```

As soon as I uncomment the "label" option which I naïvely thought would work I get the following error,

```python
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[132], line 15
9 observe_time = time_grid_from_range(time_range, time_resolution=time_resolution)
11 plot_options = {"label":dec,
12 "fmt":"-"
13 }
---> 15 plot_altitude(test_source,
16 observer,
17 observe_time,
18 ax=ax,
19 airmass_yaxis=True,
20 style_kwargs=plot_options
21 )

File ~/Applications/mambaforge/envs/swgo-plot/lib/python3.11/site-packages/astroplan/plots/time_dependent.py:402, in plot_altitude(targets, observer, time, ax, style_kwargs, style_sheet, brightness_shading, airmass_yaxis, min_altitude, min_region, max_altitude, max_region)
399 target_name = ''
401 # Plot data
--> 402 ax.plot_date(time.plot_date, masked_altitude, label=target_name, **style_kwargs)
404 # Format the time axis
405 ax.set_xlim([time[0].plot_date, time[-1].plot_date])

TypeError: matplotlib.axes._axes.Axes.plot_date() got multiple values for keyword argument 'label'
```

Is this a bug or am I using this in a wrong way?

Start in astroplan/plots/time_dependent.py at plot_altitude and the ax.plot_date call shown in the traceback. Reproduce the provided snippet, inspect how target_name and style_kwargs are combined, and ensure a caller-provided label no longer causes duplicate keyword arguments while the plotted curves retain their labels.

Written by the indexing model from the issue text.