Tileserver: handle timezone-aware request parameters

Addresses #807.

xcube/core/_tile2.py

@@ -27,6 +27,7 @@
 import PIL
 import matplotlib.colors
 import numpy as np
+import pandas as pd
 import pyproj
 import xarray as xr
 
@@ -656,6 +657,12 @@ def _get_non_spatial_labels(dataset: xr.Dataset,
                 label = coord_var[-1].values
             else:
                 try:
+                    timestamp = pd.Timestamp(label)
+                    if timestamp.tz is not None:
+                        # Convert the timestamp to timezone-naive, since
+                        # NumPy doesn't like parsing timezone-aware
+                        # representations.
+                        label = timestamp.tz_convert(None).isoformat()
                     label = np.array(label).astype(coord_var.dtype)
                 except (TypeError, ValueError) as e:
                     raise TileRequestException(