bump environment.yml

- jupyter-resource-usage==0.6.0
- jupyterlab==3.1.0
- jupyterhub-singleuser==1.4.2
- nbconvert==6.1.0
- notebook==6.4.0

repo2docker/buildpacks/conda/environment.yml

@@ -5,9 +5,9 @@ dependencies:
   - pip
   - ipywidgets==7.6.3
   - jupyter-offlinenotebook==0.2.1
-  - jupyter-resource-usage==0.5.1
-  - jupyterlab==3.0.7
-  - jupyterhub-singleuser==1.3.0
-  - nbconvert==6.0.7
-  - notebook==6.2.0
+  - jupyter-resource-usage==0.6.0
+  - jupyterlab==3.1.0
+  - jupyterhub-singleuser==1.4.2
+  - nbconvert==6.1.0
+  - notebook==6.4.0
   - nteract_on_jupyter==2.1.3