Bump up kubespawner version

2i2c-org#1103 is happening
more frequently now, and it's a hard fail - many users just can
not start up their servers. The z2jh upgrade will involve more
work (2i2c-org#1055),
so let's just bump up kubespawner in our custom hub image until then.

Fixes 2i2c-org#1103

helm-charts/images/hub/Dockerfile

@@ -12,6 +12,12 @@ ENV CONFIGURATOR_VERSION ed7e3a0df1e3d625d10903ef7d7fd9c2fbb548db
 
 RUN pip install --no-cache git+https://github.com/yuvipanda/jupyterhub-configurator@${CONFIGURATOR_VERSION}
 
+
+# Install newer version of jupyterhub-kubespawner, to bring in https://github.com/jupyterhub/kubespawner/pull/525
+# https://github.com/2i2c-org/infrastructure/issues/1103 is happening frequently enough
+# z2jh 1.2.x ships with kubespawner 1.1.0, so we just do a little bump
+RUN pip install --no-cache --upgrade jupyterhub-kubespawner==1.1.2
+
 USER root
 RUN mkdir -p /usr/local/etc/jupyterhub-configurator