chore(deps-dev): bump pestphp/pest from 1.15.0 to 1.19.0

Sourced from pestphp/pest's changelog.

<h2>v1.19.0 (2021-09-20)</h2> <h3>Added</h3>

• PHP 8.1 support (e6c7d68)
• toHaveProperties expectation (#391)

<h2>v1.18.0 (2021-08-30)</h2> <h3>Added</h3>

• toHaveLength expectation (#386)
• nunomaduro/collision:^6.0 support (4ae482c)

<h2>v1.17.0 (2021-08-26)</h2> <h3>Added</h3>

• toThrow expectation (#361)

<h2>v1.16.0 (2021-08-19)</h2> <h3>Added</h3>

• Support for new parallel options (#369)

• 58cff00 release: v1.19.0
• ae997e6 No need for --ignore-platform-req=php
• e6c7d68 Adds php-81 support
• 2f0cd7a Adds Fathom Analytics as sponsor
• 447af55 Merge pull request #391 from gabbanaesteban/master
• 253e9d1 Fix types
• 536ce1e Update snapshots
• 4331b2a Add toHaveProperties
• 8d99cac Update README.md
• 3c38fac Update README.md
• Additional commits viewable in compare view

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)