refactor(backend): Types

backend/src/middleware/auth/authentication-info.d.ts

@@ -1,11 +1,11 @@
 /**
  * Object with information about the user who is currently logged in.
  */
-export type AuthenticationInfo = {
+export interface AuthenticationInfo {
     accountType: 'student' | 'teacher';
     username: string;
     name?: string;
     firstName?: string;
     lastName?: string;
     email?: string;
-};
+}