increase minimum library version to latest from 2.x series

Author: ramunasd

composer.json

@@ -15,7 +15,7 @@
         "symfony/config":               "^4.3|^5.0",
         "symfony/yaml":                 "^4.3|^5.0",
         "symfony/console":              "^4.3|^5.0",
-        "php-amqplib/php-amqplib":      "^2.6|^3.0",
+        "php-amqplib/php-amqplib":      "^2.12|^3.0",
         "psr/log":                      "^1.0",
         "symfony/http-kernel": "^4.4|^5.0",
         "symfony/framework-bundle": "^4.4|^5.0"