python-setup-hook: use buildPackages.callPackage to not change hashes

this is just a hook so its safe

without this change:

we build a python3 for buildHost twice instead of only once while the result
of the build is the same

```
nix-repl> pkgsCross.aarch64-multiplatform.python3.pythonForBuild
«derivation /nix/store/5sx1ng86lxzggi33rchvq0z16ywkg11b-python3-3.10.7.drv»

nix-repl> pkgsCross.aarch64-multiplatform.buildPackages.python3
«derivation /nix/store/c5rlaqdfymd3j5v41rh98pjcv3dx3sh7-python3-3.10.7.drv»
```

```
$ nix-diff $(getOutForDrv "/nix/store/5sx1ng86lxzggi33rchvq0z16ywkg11b-python3-3.10.7.drv") $(getOutForDrv "/nix/store/c5rlaqdfymd3j5v41rh98pjcv3dx3sh7-python3-3.10.7.drv") --environment
- /nix/store/3fkwg2pypsxhydgwb9m7f1v5pcgfns6p-python3-3.10.7:{out}
+ /nix/store/wyhbl43ycqn43d08v5fqj1j6ynf7nz73-python3-3.10.7:{out}
• The input derivation named `python-setup-hook.sh` differs
  - /nix/store/slvn39rh0l53c9czaf3g6a4awcj63j5r-python-setup-hook.sh.drv:{out}
  + /nix/store/bcjff6dn4gp7pf0knnja9ax4qrll78d5-python-setup-hook.sh.drv:{out}
  • The set of input source names do not match:
      - cross-file.conf
  • The input derivation named `stdenv-linux` differs
    - /nix/store/rsxsipgabvny0mc286j3vfpgaaaixdyz-stdenv-linux.drv:{out}
    + /nix/store/46ywpk0p6r22y502gi21xxghminy9lbj-stdenv-linux.drv:{out}
    • The set of input derivation names do not match:
        - hook
        + acl-2.3.1
        + attr-2.5.1
        + binutils-2.39
        + binutils-wrapper-2.39
        + ed-1.18
        + expand-response-params
        + gcc-11.3.0
        + gcc-wrapper-11.3.0
        + glibc-2.35-163
        + gmp-with-cxx-stage4-6.2.1
        + libidn2-2.3.2
        + libunistring-1.0
        + linux-headers-5.19
        + pcre-8.45
        + zlib-1.2.12
    • The set of input derivations named `bzip2-1.0.8` do not match
    • The set of input derivations named `xz-5.2.6` do not match
    • The environments do not match:
        + allowedRequisites=...
        defaultNativeBuildInputs=''
        ...
    ''
  • The environments do not match:
      cmakeFlags=''
      -DCMAKE_SYSTEM_NAME=Linux -DCMAKE_SYSTEM_PROCESSOR=aarch64 -DCMAKE_HOST_SYSTEM_NAME=Linux -DCMAKE_HOST_SYSTEM_PROCESSOR=x86_64
  ''
      configureFlags=''
      --build=x86_64-unknown-linux-gnu --host=aarch64-unknown-linux-gnu
  ''
      mesonFlags=''
      --cross-file=/nix/store/0d6bflf42rgrrxhp10visp67scqncd4g-cross-file.conf
  ''
      stdenv=''
      /nix/store/6ji09gqw12pnp3ylw3rrsd65f9vhhx89-stdenv-linux/nix/store/ykjm8yzjcwg2xpf640zh6jql5s8yimkp-stdenv-linux
  ''
• The environments do not match:
    setupHook=''
    /nix/store/x6rrxsai11kl9gq29ipv0jn455admav3-python-setup-hook.sh/nix/store/h7z4wvlf7n23ir86nngjn9rpk1ygc7di-python-setup-hook.sh
''
```

pkgs/top-level/all-packages.nix

@@ -15588,7 +15588,7 @@ with pkgs;
   update-python-libraries = callPackage ../development/interpreters/python/update-python-libraries { };
 
   # Should eventually be moved inside Python interpreters.
-  python-setup-hook = callPackage ../development/interpreters/python/setup-hook.nix { };
+  python-setup-hook = buildPackages.callPackage ../development/interpreters/python/setup-hook.nix { };
 
   pythonDocs = recurseIntoAttrs (callPackage ../development/interpreters/python/cpython/docs {});