Allow pre-release (EKS) kubernetes versions (#70)

* Allow pre-release (EKS) kubernetes versions

As described in helm/helm#9371, adding `-0` to the SemVer string allows pre-release versions to be included in the permitted versions. This is necessary for installing the chart on EKS.

* fix: add explanation for kubeVersion format

As requested by @ordovicia in code review.

* fix: typo

---------

Co-authored-by: Hidehito Yabuuchi <[email protected]>

Author: alanraison

charts/gcp-workload-identity-federation-webhook/Chart.yaml

@@ -1,7 +1,9 @@
 apiVersion: v2
 name: gcp-workload-identity-federation-webhook
 description: A Helm chart for gcp-workload-identity-federation-webhook
-kubeVersion: "^1.21.0"
+# EKS versions don't follow SemVer Rules (see https://github.com/helm/helm/issues/9371),
+# so allow pre-release kubeVersions with -0 suffix.
+kubeVersion: "^1.21.0-0"
 home: https://github.com/pfnet-research/gcp-workload-identity-federation-webhook/
 # A chart can be either an 'application' or a 'library' chart.
 #