python3Packages.pulumi: fix the version number in setup.py (#176709)

the substituteInPlace didn't work for some reason, thus the deduced version became a negative one , i.e., -3.31 . Pulumi worked but then pulumi_aws was complaining that pulumi bounds were not respected.
I use sed as is done in pulumi/pulumi@d6a112c/sdk/python/Makefile#L31 to fix the issue. Now python3Packages.pulumi-aws accepts the version of pulumi and builds.

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

@@ -66,20 +66,19 @@ buildPythonPackage rec {
     black
   ];
 
-  pythonImportsCheck = ["pulumi"];
-
+  sourceRoot="source/sdk/python/lib";
+  # we apply the modifications done in the pulumi/sdk/python/Makefile
+  # but without the venv code
   postPatch = ''
-    cp README.md sdk/python/lib
-    patchShebangs .
-    cd sdk/python/lib
-
-    substituteInPlace setup.py \
-      --replace "{VERSION}" "${version}"
+    cp ../../README.md .
+    sed -i "s/\''${VERSION}/${version}/g" setup.py
   '';
 
   # disabled because tests try to fetch go packages from the net
   doCheck = false;
 
+  pythonImportsCheck = ["pulumi"];
+
   meta = with lib; {
     description = "Modern Infrastructure as Code. Any cloud, any language";
     homepage = "https://github.com/pulumi/pulumi";