python3Packages.smp: pin pyproject.toml version

Upstream uses `poetry-version-plugin` with `source = "git-tag"` to derive
the version. Tarball builds have no git tree, so the version falls back
to `"0"`, which breaks downstream version-pin checks (smpclient required
a `pythonRelaxDeps = [ "smp" ]` workaround). Substitute the version in
`pyproject.toml` instead.

Assisted-by: Claude Code (claude-opus-4-7)

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

@@ -22,6 +22,11 @@ buildPythonPackage rec {
     hash = "sha256-dATsVGG0b5SBZh7R7NT1deJFDRYi7BwtWzT7/QPjkJw=";
   };
 
+  postPatch = ''
+    substituteInPlace pyproject.toml \
+      --replace-fail 'version = "0"' 'version = "${version}"'
+  '';
+
   build-system = [
     poetry-core
   ];