Definitelytyped: Add definition for Gulp 4

[demisx]

Gulp 4 introduces new methods such as series() and parallel() that aren't part of the current gulp definition file.

[onigoetz]

I believe this was just done with #16121

[gluons]

I still haven't seen series() and parallel() in @types/gulp@4.

[Bleser]

CLI version 2.0.1
Local version 4.0.0

I have the same problem.

When I run a task, I get this error

TSError: ⨯ Unable to compile TypeScript:
gulpfile.ts(4,20): error TS2305: Module '"../../../PROJECT/node_modules/@types/gulp"' has no exported member 'series'.
gulpfile.ts(4,28): error TS2305: Module '"../../../PROJECT/node_modules/@types/gulp"' has no exported member 'parallel'.

If I transfer types for series and parallel from @ types/undertaker to @ types/gulp, the error disappears.

P.S the problem is solved by installation @types/undertaker
P.S.S Sorry for necromancy.