Update jupyterhub/configurable-http-proxy Docker tag to v4.3.2

This MR contains the following updates:

Package	Type	Update	Change
jupyterhub/configurable-http-proxy	ironbank-docker	patch	4.3.1 -> 4.3.2
jupyterhub/configurable-http-proxy		patch	4.3.1 -> 4.3.2
jupyterhub/configurable-http-proxy	stage	patch	4.3.1 -> 4.3.2

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