pythonPackages: remove name attribute`

The `buildPython*` function computes name from `pname` and `version`.
This change removes `name` attribute from all expressions in
`pkgs/development/python-modules`.

While at it, some other minor changes were made as well, such as
replacing `fetchurl` calls with `fetchPypi`.

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

@@ -1,17 +1,15 @@
 { lib
-, fetchurl
+, fetchPypi
 , buildPythonPackage
 , pythonOlder
 }:
 
-let
+buildPythonPackage rec {
   pname = "websockets";
   version = "5.0.1";
-in buildPythonPackage rec {
-  name = "${pname}-${version}";
 
-  src = fetchurl {
-    url = "mirror://pypi/${builtins.substring 0 1 pname}/${pname}/${name}.tar.gz";
+  src = fetchPypi {
+    inherit pname version;
     sha256 = "a49d315db5a7a19d55422e1678e8a1c3b9661d7296bef3179fa620cf80b12674";
   };