chore(deps): upgrade jenkins-x-plugins/jx-secret to version 0.4.15

from: https://github.com/jenkins-x-plugins/jx-secret.git

-----
# jenkins-x-plugins/jx-secret

## Changes in version 0.4.15

### Bug Fixes

* increase timeouts (Mårten Svantesson)

### Chores

* deps: upgrade go dependencies (Mårten Svantesson)

Author: pow-devops2020

pkg/plugins/versions.go

@@ -34,7 +34,7 @@ const (
 	PromoteVersion = "0.6.26"
 
 	// SecretVersion the version of the jx secret plugin
-	SecretVersion = "0.4.14"
+	SecretVersion = "0.4.15"
 
 	// TestVersion the version of the jx test plugin
 	TestVersion = "0.4.9"