Bump Helm support to 3.21.0 and 4.2.0 (#2588)

* chore: bump pinned helm versions

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Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

* fix: align kubernetes module pins for helm bump

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Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

* docs: clarify helm and k8s version pins

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* test: update helm 4 snapshot outputs

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* test: update helm 4 postrender integration fixture

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* test: update helm 4 postrender template fixture

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Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

.github/workflows/Makefile

@@ -1,4 +1,4 @@
-HELM_VERSION ?= v4.1.0
+HELM_VERSION ?= v4.2.0
 KUSTOMIZE_VERSION ?= v5.8.0
 K8S_VERSION ?= v1.34.0
 MINIKUBE_VERSION ?= v1.37.0