Drupal 10 uses guzzlehttp/psr7 for PSR-17 services and therefore it should be a direct dependency

Problem/Motivation

In Drupal 8 and 9, Drupal had an indirect dependency on guzzlehttp/psr7 because Guzzle uses it internally to create Request and Response objects.

In Drupal 10, numerous core services depend on guzzlehttp/psr7 as our PSR-17 implementation, so we should add a direct dependency and constraint for it.

Proposed resolution

Add a direct dependency on the guzzlehttp/psr7 package.

Remaining tasks

TBD

User interface changes

N/A

API changes

N/A

Data model changes

N/A

Release notes snippet

Drupal core now has a direct dependency on the guzzlehttp/psr7 package (previously an indirect dependency) since it is used for the default implementation of several core services for PSR-17.