python3Packages: provide setuptools-scm with toml[i] by default and remove duplicated toml packages

Some packages seem to still require toml despite setuptools-scm having switched to tomli.
If it is missing the version number in dist.into is set to 0.0.0 and silently all version pins break.

pkgs/development/python-modules/ansi2html/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi, isPy3k, six, mock, pytestCheckHook, setuptools, setuptools-scm, toml }:
+{ lib, buildPythonPackage, fetchPypi, isPy3k, six, mock, pytestCheckHook, setuptools, setuptools-scm }:
 
 buildPythonPackage rec {
   pname = "ansi2html";
@@ -11,7 +11,7 @@ buildPythonPackage rec {
     sha256 = "0f124ea7efcf3f24f1f9398e527e688c9ae6eab26b0b84e1299ef7f94d92c596";
   };
 
-  nativeBuildInputs = [ setuptools-scm toml ];
+  nativeBuildInputs = [ setuptools-scm ];
   propagatedBuildInputs = [ six setuptools ];
 
   preCheck = "export PATH=$PATH:$out/bin";