Cannot create a shoreline vector with a single point in create_complete_line_string

[2320sharon]

This error occurs because only a single shoreline was discovered for a given date which means it cannot be saved as a linestring. Instead save it as a shapely.Point.

Bug reported by @mlundine

Saved extracted shorelines to /home/aksup/doodleverse/CoastSeg/sessions/ID_krt21_datetime04-04-24__11_42_37_RGB
Computing transect shoreline intersections: 100%|█████████████████████████████████████████████████████████████████████████████████████████████| 1319/1319 [05:06<00:00,  4.30it/s]Traceback (most recent call last):
  File "/home/aksup/doodleverse/CoastSeg/alaska_zoo_test.py", line 110, in <module>
    zoo_model_instance.extract_shorelines_with_unet(settings=settings,
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/zoo_model.py", line 932, in extract_shorelines_with_unet
    common.save_transects(
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/common.py", line 1927, in save_transects
    merged_timeseries_df,timeseries_df = add_lat_lon_to_timeseries(merged_timeseries_df, transects_gdf.to_crs('epsg:4326'),cross_distance_df,
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/common.py", line 1801, in add_lat_lon_to_timeseries
    new_gdf_shorelines_wgs84=convert_points_to_linestrings(cross_shore_pts, group_col='date', output_crs='epsg:4326')
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/common.py", line 2026, in convert_points_to_linestrings
    linestrings_gdf = order_linestrings_gdf(linestrings_gdf,linestrings_gdf['date'],output_crs=output_crs)
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/common.py", line 1681, in order_linestrings_gdf
    line_string = create_complete_line_string(points)
  File "/home/aksup/doodleverse/CoastSeg/src/coastseg/common.py", line 1656, in create_complete_line_string
    return LineString(sorted_points)
  File "/home/aksup/miniconda3/envs/coastseg_gym/lib/python3.10/site-packages/shapely/geometry/linestring.py", line 73, in __new__
    geom = shapely.linestrings(coordinates)
  File "/home/aksup/miniconda3/envs/coastseg_gym/lib/python3.10/site-packages/shapely/decorators.py", line 77, in wrapped
    return func(*args, **kwargs)
  File "/home/aksup/miniconda3/envs/coastseg_gym/lib/python3.10/site-packages/shapely/creation.py", line 120, in linestrings
    return lib.linestrings(coords, out=out, **kwargs)
shapely.errors.GEOSException: IllegalArgumentException: point array must contain 0 or >1 elements