Changes related to the next MeiliSearch release (v0.19.0)

[meili-bot]

This PR gathers the changes related to the next MeiliSearch release (v0.19.0) so that this package is ready when the official release is out.

⚠️ This PR should NOT be merged until:

• the next release of MeiliSearch (v0.19.0) is out.
• the meilisearch-php dependency has been released to be compatible with MeiliSearch v0.19.0. Once the release is out, the meilisearch-php version in this package should be upgraded and committed to this branch.

This PR is auto-generated for the pre-release week purpose.

[bors[bot]]

Build succeeded:

• linter-check
• tests (php 7.2)
• tests (php 7.3)
• tests (php 7.4)
• tests (php 8.0)