Remove '--follow-imports silent' from mypy args

This essentially reverts 83df547.

The main reason for doing this is that this is not the default option
when running `mypy`, which means that (absent other configuration)
running `mypy .` and using `pylsp-mypy` will invalidate each others
caches, which will cause both things to slow down.

`--follow-imports silent` is also incompatible with `dmypy`, so
working around this issue by specifying `follow_imports = 'silent'` in
your `pyproject.toml` is a non-starter if you want to use `dmypy`.

Closes python-lsp#81

pylsp_mypy/plugin.py

@@ -301,7 +301,7 @@ def get_diagnostics(
     exit_status = 0
 
     if not dmypy:
-        args.extend(["--incremental", "--follow-imports", "silent"])
+        args.extend(["--incremental"])
         args = apply_overrides(args, overrides)
 
         if shutil.which("mypy"):