treewide: with stdenv.lib; in meta -> with lib;

Part of: https://github.com/NixOS/nixpkgs/issues/108938

meta = with stdenv.lib;

is a widely used pattern. We want to slowly remove
the `stdenv.lib` indirection and encourage people
to use `lib` directly. Thus let’s start with the meta
field.

This used a rewriting script to mostly automatically
replace all occurances of this pattern, and add the
`lib` argument to the package header if it doesn’t
exist yet.

The script in its current form is available at
https://cs.tvl.fyi/depot@2f807d7f141068d2d60676a89213eaa5353ca6e0/-/blob/users/Profpatsch/nixpkgs-rewriter/default.nix

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

@@ -1,4 +1,4 @@
-{ stdenv, fetchPypi, python, buildPythonPackage, isPy3k, pycairo, backports_functools_lru_cache
+{ lib, stdenv, fetchPypi, python, buildPythonPackage, isPy3k, pycairo, backports_functools_lru_cache
 , which, cycler, dateutil, nose, numpy, pyparsing, sphinx, tornado, kiwisolver
 , freetype, libpng, pkgconfig, mock, pytz, pygobject3, gobject-introspection
 , certifi, pillow
@@ -68,7 +68,7 @@ buildPythonPackage rec {
   # order for all of the tests to pass.
   doCheck = false;
 
-  meta = with stdenv.lib; {
+  meta = with lib; {
     description = "Python plotting library, making publication quality plots";
     homepage    = "https://matplotlib.org/";
     maintainers = with maintainers; [ lovek323 veprbl ];