Pin scikit-learn and pandas to specific versions

- Required by `nilearn`

Author: HippocampusGirl

Dockerfile

@@ -123,9 +123,9 @@ RUN conda install -y python=3.7.1 \
                      mkl-service \
                      numpy=1.19 \
                      scipy=1.5 \
-                     'scikit-learn>=0.21' \
+                     scikit-learn=0.21 \
                      matplotlib=2.2.2 \
-                     pandas=0.23.4 \
+                     pandas=0.24 \
                      libxml2=2.9.8 \
                      libxslt=1.1.32 \
                      graphviz=2.40.1 \