Ignore failing doctests due to pydata/xarray#4753

Author: tomwhite

setup.cfg

@@ -67,7 +67,8 @@ bgen =
 fail_under = 100
 
 [tool:pytest]
-addopts = --doctest-modules --ignore=validation --cov-fail-under=100
+# TODO: remove ignored doctests below once Xarray>0.18.2 is released (with https://github.com/pydata/xarray/pull/4753)
+addopts = --doctest-modules --ignore=validation --cov-fail-under=100 --ignore=sgkit/stats/regenie.py --ignore=sgkit/stats/pca.py
 norecursedirs = .eggs build docs
 filterwarnings =
     error