fix: change WorkflowStep into an abstract class (#2916)

For some reason, Typescript resolves types in a different away compared
to abstract classes. As a consequence, it would not apply the
overloading properly and always treats WorkflowStep.do as a 3 argument function

types/defines/rpc.d.ts

@@ -233,26 +233,12 @@ declare module "cloudflare:workers" {
  timestamp: Date;
  };
 
- export type WorkflowStep = {
- do:
- | (<T extends Rpc.Serializable<T>>(
- name: string,
- callback: () => Promise<T>
- ) => Promise<T>)
- | (<T extends Rpc.Serializable<T>>(
- name: string,
- config: WorkflowStepConfig,
- callback: () => Promise<T>
- ) => Promise<T>)
- | (<T extends Rpc.Serializable<T>>(
- name: string,
- config: WorkflowStepConfig | (() => Promise<T>),
- callback?: () => Promise<T>
- ) => Promise<T>);
-
+ export abstract class WorkflowStep {
+ do<T extends Rpc.Serializable<T>>(name: string, callback: () => Promise<T>): Promise<T>;
+ do<T extends Rpc.Serializable<T>>(name: string, config: WorkflowStepConfig, callback: () => Promise<T>): Promise<T>;
  sleep: (name: string, duration: WorkflowSleepDuration) => Promise<void>;
  sleepUntil: (name: string, timestamp: Date | number) => Promise<void>;
- };
+ }
 
  export abstract class WorkflowEntrypoint<
  Env = unknown,