Optimise image size a little

.dockerignore

@@ -1 +1,14 @@
 .git
+test_data
+bin
+CHANGELOG.md
+data
+lib
+LICENSE
+main.nf
+nextflow.config
+README.md
+test_data
+# we typically run tests with outputs to these:
+output
+work

Dockerfile

@@ -9,7 +9,11 @@ RUN \
     && micromamba install -n base --file $HOME/environment.yaml \
     && micromamba clean --all --yes \
     && fix-permissions $CONDA_DIR \
-    && fix-permissions $HOME
+    && fix-permissions $HOME \
+    && rm -rf $CONDA_DIR/conda-meta \
+    && rm -rf $CONDA_DIR/include \
+    && rm -rf $CONDA_DIR/lib/python3.*/site-packages/pip \
+    && find $CONDA_DIR -name '__pycache__' -type d -exec rm -rf '{}' '+'
 
 USER $WF_UID
 WORKDIR $HOME