feat: allow_update_branch argument

setting allows toggling "always suggest updating pull request branch"
repository setting

Signed-off-by: Sean Trantalis <strantalis@virtru.com>

github/resource_github_repository.go

@@ -263,6 +263,10 @@ func resourceGithubRepository() *schema.Resource {
 				Type:     schema.TypeInt,
 				Computed: true,
 			},
+			"allow_update_branch": {
+				Type:     schema.TypeBool,
+				Optional: true,
+			},
 		},
 	}
 }
@@ -309,6 +313,7 @@ func resourceGithubRepositoryObject(d *schema.ResourceData) *github.Repository {
 		GitignoreTemplate:        github.String(d.Get("gitignore_template").(string)),
 		Archived:                 github.Bool(d.Get("archived").(bool)),
 		Topics:                   expandStringList(d.Get("topics").(*schema.Set).List()),
+		AllowUpdateBranch:        github.Bool(d.Get("allow_update_branch").(bool)),
 	}
 }
 
@@ -465,6 +470,7 @@ func resourceGithubRepositoryRead(d *schema.ResourceData, meta interface{}) erro
 	d.Set("topics", flattenStringList(repo.Topics))
 	d.Set("node_id", repo.GetNodeID())
 	d.Set("repo_id", repo.GetID())
+	d.Set("allow_update_branch", repo.GetAllowUpdateBranch())
 
 	if repo.GetHasPages() {
 		pages, _, err := client.Repositories.GetPagesInfo(ctx, owner, repoName)

website/docs/r/repository.html.markdown

@@ -113,6 +113,8 @@ initial repository creation and create the target branch inside of the repositor
 
 * `ignore_vulnerability_alerts_during_read` (Optional) - Set to `true` to not call the vulnerability alerts endpoint so the resource can also be used without admin permissions during read.
 
+* `allow_update_branch` (Optional) - Set to `true` to always suggest updating pull request branches.
+
 ### GitHub Pages Configuration
 
 The `pages` block supports the following: