Remove out-of-date Symfony 4 note

README.md

@@ -86,12 +86,6 @@ Check the [docker-compose](https://docs.docker.com/compose/reference/overview/)
 #### Local
 Runs the command on the local system.
 
-## Symfony 4
-
-The Symfony Process component has different typehints in the parameters of several APIs in Symfony 4 than Symfony 3 does. This is due to the fact that Symfony 4 requires PHP 7.1.3 or later, which supports a number of typehints not permitted in earlier PHP versions. This difference is minor for most clients, but presents problems for code that subclasses Process, as it is not possible to be compatible with both the Symofny 3 and the Symfony 4 typehints at the same time.
-
-In the future, Symfony 4 will be supported in this library on a separate branch.
-
 ## Running the tests
 
 The test suite may be run locally by way of some simple composer scripts: