refactor: Use beforeRequest hook with slack app

packages/backend/src/apps/slack/common/add-auth-header.ts

@@ -0,0 +1,11 @@
+import { TBeforeRequest } from '@automatisch/types';
+
+const addAuthHeader: TBeforeRequest = ($, requestConfig) => {
+  if (requestConfig.headers && $.auth.data?.accessToken) {
+    requestConfig.headers.Authorization = `Bearer ${$.auth.data.accessToken}`;
+  }
+
+  return requestConfig;
+};
+
+export default addAuthHeader;