Avoid deprecated use_cftime (#461)

### What kind of change does this PR introduce?

* Avoid use of `use_cftime` to adapt to the deprecation in the latest
xarray.

### Does this PR introduce a breaking change?
No.

AUTHORS.rst

@@ -19,3 +19,4 @@ Contributors
 ------------
 
 * Louise Arnal <arnal.louise@ouranos.ca> `@lou-a <https://github.com/lou-a>`_
+* Pascal Bourgault <bourgault.pascal@ouranos.ca> `@aulemahal <https://github.com/aulemaha>`_

src/ravenpy/utilities/forecasting.py

@@ -297,13 +297,16 @@ def _shift_esp_time(nc, year, dim="member"):
 
     Modify time such that it starts on the given year, and add member dimension with original year as value.
     """
-    ds = xr.open_dataset(nc, use_cftime=True)
+    ds = xr.open_dataset(nc)
 
     # Create new time coordinate
-    start = ds.time.data[0]
+    start = ds.indexes["time"][0]
     freq = xr.infer_freq(ds.time)
-    ds["time"] = xr.cftime_range(
-        start.replace(year=year), periods=len(ds.time), freq=freq
+    ds["time"] = xr.date_range(
+        start.replace(year=year),
+        periods=len(ds.time),
+        freq=freq,
+        calendar=ds.time.dt.calendar,
     )
 
     # New coordinate dimension to store the original year