Upgrade fixer (php-pm#550)

Merge pull request php-pm#541 from dave-redfern/support-sf6

Add Symfony 6 support

Merge pull request php-pm#542 from mathieudz/disable_keepalive

Block keep-alive in HTTP 1.1

Temporarily prevent installing reactphp/http >=1.3

There seems to be a problem with the newest react keepalive feature, avoiding that release until further investigations are conducted see php-pm#538

remove unused react cache dependency (php-pm#534)

Merge pull request php-pm#527 from acasademont/php8

Add php8 support

Remove unwanted var_dump

Merge pull request php-pm#515 from acasademont/properly_log_slave_errors

Properly log error events emitted by the slave HttpServer

Merge pull request php-pm#505 from klemenb/master

Support for configuring max. concurrent requests and request body buffer

Merge pull request php-pm#504 from clue-labs/reactphp-http

Update react/http to v1.0.0