Use version of guzzlehttp/guzzle ^6.5.2

Problem/Motivation

Based on #3091418-25: Update composer dependencies on 9.0.x and #3091418-46: Update composer dependencies on 9.0.x we need to set a minimum version of guzzlehttp/guzzle to 6.5.2.

Proposed resolution

Set the new version, update our composer.lock file, commit.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet