ignore the pkg_resources deprecation warning (pydata#7594)

Author: keewis

xarray/tests/__init__.py

@@ -38,6 +38,7 @@
 # https://github.com/pydata/xarray/issues/7322
 warnings.filterwarnings("ignore", "'urllib3.contrib.pyopenssl' module is deprecated")
 warnings.filterwarnings("ignore", "Deprecated call to `pkg_resources.declare_namespace")
+warnings.filterwarnings("ignore", "pkg_resources is deprecated as an API")
 
 arm_xfail = pytest.mark.xfail(
     platform.machine() == "aarch64" or "arm" in platform.machine(),