python: get rid of msgpack-python, fixes #48864

We already have msgpack, which is the same. Building a Python env with
`spacy` resulted in a collision between an `.so` provided through both
`msgpack` and `msgpack-python`.

I don't know why `transitional = True` was set. These kind of things
should be documented!

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

@@ -15,7 +15,7 @@
 , regex
 , cymem
 , pathlib
-, msgpack-python
+, msgpack
 , msgpack-numpy
 , jsonschema
 , blis
@@ -50,7 +50,7 @@ buildPythonPackage rec {
    requests
    regex
    ftfy
-   msgpack-python
+   msgpack
    msgpack-numpy
    jsonschema
    blis