Changing webpack compiler hook from emit to afterEmit

[geldmacher]

Is your feature request related to a problem? Please describe.
It is not possible to access the emitted files in the processOutput function.

Describe the solution you'd like
Changing the webpack compiler hook from emit to afterEmit solves the problem.

[ztoben]

So this was originally changed during the webpack 5 upgrade because it would throw a warning for using emit rather than afterEmit, but testing it locally really quick it looks like that no longer happens so I'll get it changed back.

[ztoben]

@geldmacher should be fixed in v6.1.0. Thanks again!