Require at least blas 1.1

Require at least blas 1.1; otherwise other packages dependencies may
attempt to downgrade it.

scipy-notebook/Dockerfile

@@ -18,7 +18,7 @@ USER $NB_UID
 # Remove pyqt and qt pulled in for matplotlib since we're only ever going to
 # use notebook-friendly backends in these images
 RUN conda install --quiet --yes \
-    'blas=*=openblas' \
+    'blas=1.1*=openblas' \
     'ipywidgets=7.2*' \
     'pandas=0.22*' \
     'numexpr=2.6*' \