sec: Mitigate the attack surface of potential malicious injection (#24)

Simplify error message for route not found

- This change attempts to leave less room to potential attacks possible when double quotes are use without prior sanitize or type enforcement.
- By using plain text with single quote we mitigate the issue.

Author: alexandreelise

src/Services/Routes.php

@@ -107,7 +107,7 @@ public function offsetGet($path) : array
             return $this->routes[$path];
         }
 
-        throw new InvalidArgumentException("Route $path not found.");
+        throw new InvalidArgumentException('Route not found.');
     }
 
     /**