feat: add input to enable gpg commit signing

src/create-or-update-branch.ts

@@ -91,7 +91,8 @@ export async function createOrUpdateBranch(
   base: string,
   branch: string,
   branchRemoteName: string,
-  signoff: boolean
+  signoff: boolean,
+  gpgSign: boolean
 ): Promise<CreateOrUpdateBranchResult> {
   // Get the working base.
   // When a ref, it may or may not be the actual base.
@@ -124,6 +125,9 @@ export async function createOrUpdateBranch(
     if (signoff) {
       params.push('--signoff')
     }
+    if (gpgSign) {
+      params.push('--gpg-sign')
+    }
     await git.commit(params)
   }