pinned guzzle version for PHP 7.2

Author: agrzegorzewski

.github/workflows/test-package.yml

@@ -12,7 +12,7 @@ jobs:
         guzzle-version: ['^5.3', '^6.0']
         include:
         - php-version: '7.2'
-          guzzle-version: '^7.0'
+          guzzle-version: '<7.3'
         - php-version: '7.3'
           guzzle-version: '^7.0'
         - php-version: '7.4'