Add TODO comments for pinning system packages

This facilitates reproducible builds.

Author: jsf9k

Dockerfile

@@ -44,6 +44,9 @@ RUN python3 -m pip install --no-cache-dir --upgrade \
 # Install everything we need to build wheels
 #
 # TODO: Remove any packages we don't need.  See #105 for more details.
+#
+# TODO: Pin these packages to enable reproducible builds.  See #106
+# for more details.
 ###
 ENV DEPS="build-essential \
     cmake \
@@ -127,6 +130,9 @@ RUN groupadd --system --gid ${CISA_GID} ${CISA_GROUP} \
 # TODO: Remove any packages we don't need.  See #105 for more details.
 # For example, it should be possible to install libblas-dev above but
 # only install libblas here.
+#
+# TODO: Pin these packages to enable reproducible builds.  See #106
+# for more details.
 ###
 ENV DEPS="build-essential \
     cmake \