Update argoproj/argocd Docker tag to v1.8.4

This MR contains the following updates:

Package	Type	Update	Change
argoproj/argocd	ironbank-docker	patch	v1.8.3 -> v1.8.4
argoproj/argocd		patch	v1.8.3 -> v1.8.4
argoproj/argocd	stage	patch	v1.8.3 -> v1.8.4

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