Avoid PEP 585 and PEP 604 rewrites

This setting is only applicable when the target Python version is
below 3.9 and 3.10 respectively.

Author: DimitriPapadopoulos

pyproject.toml

@@ -291,6 +291,9 @@ ban-relative-imports = "all"
 [tool.pytest.ini_options]
 addopts = ["--strict-config", "--strict-markers"]
 
+[lint.pyupgrade]
+keep-runtime-typing = true
+
 # We want to forbid warnings from within xarray in our tests — instead we should
 # fix our own code, or mark the test itself as expecting a warning. So this:
 # - Converts any warning from xarray into an error