fix: helm-chart/images/binderhub/requirements.txt to reduce vulnerabi…

…lities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-JUPYTERHUB-7654158

helm-chart/images/binderhub/requirements.txt

@@ -63,7 +63,7 @@ jsonschema==3.2.0
     #   jupyter-telemetry
 jupyter-telemetry==0.1.0
     # via jupyterhub
-jupyterhub==1.4.2
+jupyterhub==4.1.6
     # via
     #   -r binderhub.in
     #   -r requirements.in