build: bump php-http/mock-client

Author: JaZo

composer.json

@@ -25,7 +25,7 @@
     "require": {
         "php": "^7.4|^8.0",
         "php-http/discovery": "^1.14",
-        "php-http/mock-client": "^1.5",
+        "php-http/mock-client": "^1.6",
         "psr/http-factory": "^1.0",
         "psr/http-message": "^1.0|^2.0",
         "symfony/string": "^5.4|^6.0"