Add missing argument

`->dump` has 5 arguments (the 3th argument, the indent, was not provided in the twig extension).

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | let's see
| Fixed tickets | -
| License       | MIT
| Doc PR        | -