Issue #3357247 by Spokje: Update guzzlehttp/psr7

Author: catch

composer.json

@@ -16,7 +16,7 @@
         "egulias/email-validator": "~3.2.1",
         "guzzlehttp/guzzle": "~6.5.8",
         "guzzlehttp/promises": "~1.5.2",
-        "guzzlehttp/psr7": "~1.9.0",
+        "guzzlehttp/psr7": "~1.9.1",
         "laminas/laminas-diactoros": "~2.14.0",
         "laminas/laminas-escaper": "~2.9.0",
         "laminas/laminas-feed": "~2.17.0",