coops: Specify CRS in GeoDataFrame

Geopandas was throwing a warning in `searvey.get_stations()`:

    UserWarning: CRS not set for some of the concatenation inputs.
    Setting output's CRS as WGS 84 (the single non-null crs provided)

The IOC and USGS GeoDataFrames do specify the CRS, so now we do it for
COOPS, too.

searvey/coops.py

@@ -789,7 +789,7 @@ def coops_stations(station_status: StationStatus | None = None) -> GeoDataFrame:
 
     return GeoDataFrame(
         stations[["nws_id", "name", "state", "status", "removed"]],
-        geometry=geopandas.points_from_xy(stations["x"], stations["y"]),
+        geometry=geopandas.points_from_xy(stations["x"], stations["y"], crs="EPSG:4326"),
     )