docker: ensure latest birdy 0.8.5 for RavenPy nb fixes

To pull this change bird-house/birdy#240.

To fix this error bird-house/birdy#239:
```
RavenPy-master/docs/notebooks/02_Extract_geographical_watershed_properties.ipynb::Cell 5
AttributeError: module 'xarray' has no attribute 'open_rasterio'
```

docker/environment.yml

@@ -40,7 +40,7 @@ dependencies:
   - numpy
   # TODO: unpin cf_xarray due to https://github.com/xarray-contrib/cf-xarray/issues/442
   - cf_xarray != 0.8.1
-  - birdy
+  - birdy >= 0.8.5
     # - owslib>=0.23.0  # from ravenpy
     # - netcdf4  # from ravenpy
   # TODO: remove libnetcdf PIN because https://github.com/Ouranosinc/PAVICS-landing/issues/66