feat: add ruleset target push (#2351)

Refs: #2235

Co-authored-by: Keegan Campbell <[email protected]>

Author: anelam

github/resource_github_organization_ruleset.go

@@ -34,8 +34,8 @@ func resourceGithubOrganizationRuleset() *schema.Resource {
 			"target": {
 				Type:         schema.TypeString,
 				Required:     true,
-				ValidateFunc: validation.StringInSlice([]string{"branch", "tag"}, false),
-				Description:  "Possible values are `branch` and `tag`.",
+				ValidateFunc: validation.StringInSlice([]string{"branch", "tag", "push"}, false),
+				Description:  "Possible values are `branch`, `tag` and `push`. Note: The `push` target is in beta and is subject to change.",
 			},
 			"enforcement": {
 				Type:         schema.TypeString,