Update kubectl to v1.28.3, nginx to 1.25.3

This MR contains the following updates:

Package	Update	Change
registry1.dso.mil/ironbank/opensource/kubernetes/kubectl	patch	v1.28.2 -> v1.28.3
registry1.dso.mil/ironbank/opensource/nginx/nginx	patch	1.25.2 -> 1.25.3

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