Update module github.com/hashicorp/vault/api to v1.21.0

Author: renovate[bot]

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/go-logr/logr v1.4.2
 	github.com/hashicorp/go-multierror v1.1.1
 	github.com/hashicorp/hcl/v2 v2.21.0
-	github.com/hashicorp/vault/api v1.14.0
+	github.com/hashicorp/vault/api v1.21.0
 	github.com/onsi/ginkgo/v2 v2.19.0
 	github.com/onsi/gomega v1.33.1
 	github.com/pkg/errors v0.9.1