Ask bug reporters to confirm they're using a recent version of xarray (#8283)

Author: max-sixty

.github/ISSUE_TEMPLATE/bugreport.yml

@@ -44,6 +44,7 @@ body:
         - label: Complete example — the example is self-contained, including all data and the text of any traceback.
         - label: Verifiable example — the example copy & pastes into an IPython prompt or [Binder notebook](https://mybinder.org/v2/gh/pydata/xarray/main?urlpath=lab/tree/doc/examples/blank_template.ipynb), returning the result.
         - label: New issue — a search of GitHub Issues suggests this is not a duplicate.
+        - label: Recent environment — the issue occurs with the latest version of xarray and its dependencies.
 
   - type: textarea
     id: log-output