use sphinx=1.7.5 on windows

Chilipp · Chilipp · commit 2705ae77738e · 2019-09-15T18:00:08.000+02:00
diff --git a/tests/envs/environment_py3.7_qt5.yml b/tests/envs/environment_py3.7_qt5.yml
@@ -9,7 +9,8 @@ dependencies:
     - xarray
     - netCDF4
     - pyqt>5.7
-    - sphinx
+    - sphinx  # [not win]
+    - sphinx=1.7.5  # [win]
     - pip:
         - pytest
         - pytest-cov
