Add ^1.0.0 version to rector/rector

[mmatsoo]

Description

A recent Renovate attempt to update to palantirnet/drupal-rector ^0.20.0 is borking and my troubleshooting found that
palantir/drupal-rector requires rector/rector ^1.0 and usher allows up to 0.19.0.

(In the error message below, it reports usher can use up to 0.18.13 though 0.19.0 is also allowed in composer.json.)

- chromatic/usher v4.0.0 requires rector/rector ^0.16.0 || ^0.17.0 || ^0.18.0 -> satisfiable by rector/rector[0.16.0, ..., 0.18.13].
- palantirnet/drupal-rector[0.20.0, ..., 0.20.1] require rector/rector ^1.0 -> satisfiable by rector/rector[1.0.0, 1.0.1, 1.0.2, 1.0.3].

[mmatsoo]

Oops, this is a repeat of #201. Closing this PR.