Merge pull request #6229 from W0rma/guzzle-psr7-v2

Allow installation of guzzlehttp/psr7:^2.0

Author: Naktibalda

composer.json

@@ -20,7 +20,7 @@
  "ext-json": "*",
  "ext-mbstring": "*",
  "codeception/lib-asserts": "^1.0",
- "guzzlehttp/psr7": "~1.4",
+ "guzzlehttp/psr7": "^1.4 | ^2.0",
  "symfony/finder": ">=2.7 <6.0",
  "symfony/console": ">=2.7 <6.0",
  "symfony/event-dispatcher": ">=2.7 <6.0",