Add support for SHA256 repositories

New input parameter to specify the git object format when initializing a
git repository.

__test__/git-auth-helper.test.ts

@@ -824,7 +824,8 @@ async function setup(testName: string): Promise<void> {
     sshUser: '',
     workflowOrganizationId: 123456,
     setSafeDirectory: true,
-    githubServerUrl: githubServerUrl
+    githubServerUrl: githubServerUrl,
+    objectFormat: undefined
   }
 }