[TASK] Update guzzlehttp/guzzle dependency to 6.3.0

This brings PHP 7.2 support for guzzle functionality.

Verified that guzzle still runs with PHP7.0 (min requirement for us)

Resolves: #82313
Releases: master, 8.7
Change-Id: I65b27c41d49dcb8b740b6f276da305df864ff50e
Reviewed-on: https://review.typo3.org/53924


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>