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/u-msgpack-python/default.nix

@@ -1,6 +1,6 @@
 { buildPythonPackage
 , lib
-, fetchurl
+, fetchPypi
 , glibcLocales
 , python
 }:
@@ -8,10 +8,9 @@
 buildPythonPackage rec {
   pname = "u-msgpack-python";
   version = "2.5.0";
-  name = "${pname}-${version}";
 
-  src = fetchurl {
-    url = "mirror://pypi/${builtins.substring 0 1 pname}/${pname}/${name}.tar.gz";
+  src = fetchPypi {
+    inherit pname version;
     sha256 = "7ff18ae3721fa75571f9329c08f7c0120416a6ae36194bd8674f65b3b78d0702";
   };