Update Helm release kube-prometheus-stack to 78.3.x

This MR contains the following updates:

Package	Update	Change
kube-prometheus-stack (source)	minor	78.2.x -> 78.3.x

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Release Notes

prometheus-community/helm-charts (kube-prometheus-stack)

v78.3.0

Compare Source

kube-prometheus-stack collects Kubernetes manifests, Grafana dashboards, and Prometheus rules combined with documentation and scripts to provide easy to operate end-to-end Kubernetes cluster monitoring with Prometheus using the Prometheus Operator.

What's Changed

• [kube-prometheus-stack] Support validating AlertmanagerConfigs by @​vladimirpetr in #​6244

Full Changelog: https://github.com/prometheus-community/helm-charts/compare/prometheus-27.41.0...kube-prometheus-stack-78.3.0

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