v4.0.1 introduced breaking change (express v4 -> v5 bump)

[caugner]

In #715, express was upgraded from v4 to v5.

Since express types are used in the public interface of @google/functions-framework, this appears to be a breaking change for users of this library:

• The signature of the public http() function has changed:
  

  functions-framework-nodejs/src/function_registry.ts

  Lines 86 to 88 in 34e75c8

  	export const http = (functionName: string, handler: HttpFunction): void => {
  	register(functionName, 'http', handler);
  	};

• The second parameter uses the HttpFunction type:
  

  functions-framework-nodejs/src/functions.ts

  Lines 58 to 60 in 34e75c8

  	export interface HttpFunction {
  	(req: Request, res: Response): any;
  	}

• This type uses Request and Response from express:
  

  functions-framework-nodejs/src/functions.ts

  Line 19 in 34e75c8

  import {Request as ExpressRequest, Response} from 'express';

[akerekes]

Release has been updated to v5.0.0