exabgp: add raitobezarius as a maintainer

pkgs/servers/networking/exabgp/default.nix

···
     homepage = "https://github.com/Exa-Networks/exabgp";
     changelog = "https://github.com/Exa-Networks/exabgp/blob/${src.rev}/CHANGELOG.rst";
     license = licenses.bsd3;
-    maintainers = with maintainers; [ hexa ];
+    maintainers = with maintainers; [ hexa raitobezarius ];
   };
 }