To be compatible to symfony 5

[xfontanet]

hello,

the compatiblity to the new version of Symfony 5 is not available .

indeed in Wa72\JsonRpcBundle\DependencyInjection\Configuration.php file, object TreeBuilder change :
line 22-23

$treeBuilder = new TreeBuilder();
$rootNode= $treeBuilder->root('wa72_json_rpc');

new object TreeBuilder is instance as it now :

`
$treeBuilder = new TreeBuilder('wa72_json_rpc');

$rootNode =$treeBuilder->getRootNode();
`

if you can change it that is grateful

take care.