[BUG] yumpkg is broken for Python<3.8

[hurzhurz]

Description
Since 3006.9 yumpkg does not work anymore on systems with Python versions below 3.8.
This is relevant for example when using salt-ssh.

The cause is simply the usage of the assignment/named expression in this fix: 00f6d42

This is the result when trying to use the pkg module with salt-ssh on a system with Python 3.6.8:

# salt-ssh xyz pkg.list_pkgs
xyz:
    ----------
    retcode:
        255
    stderr:
        'pkg.list_pkgs' is not available.
    stdout:

    [ERROR   ] Failed to import module kernelpkg_linux_yum, this is due most likely to a syntax error:
    Traceback (most recent call last):
      File "/var/tmp/.root_78a1bd_salt/pyall/salt/loader/lazy.py", line 785, in _load_module
        mod = self.run(spec.loader.load_module)
      File "/var/tmp/.root_78a1bd_salt/pyall/salt/loader/lazy.py", line 1245, in run
        return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs)
      File "/var/tmp/.root_78a1bd_salt/py3/contextvars/__init__.py", line 38, in run
        return callable(*args, **kwargs)
      File "/var/tmp/.root_78a1bd_salt/pyall/salt/loader/lazy.py", line 1260, in _run_as
        ret = _func_or_method(*args, **kwargs)
      File "<frozen importlib._bootstrap_external>", line 399, in _check_name_wrapper
      File "<frozen importlib._bootstrap_external>", line 823, in load_module
      File "<frozen importlib._bootstrap_external>", line 682, in load_module
      File "<frozen importlib._bootstrap>", line 265, in _load_module_shim
      File "<frozen importlib._bootstrap>", line 684, in _load
      File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
      File "<frozen importlib._bootstrap_external>", line 678, in exec_module
      File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
      File "/var/tmp/.root_78a1bd_salt/pyall/salt/modules/kernelpkg_linux_yum.py", line 8, in <module>
        import salt.modules.yumpkg
      File "/var/tmp/.root_78a1bd_salt/pyall/salt/modules/yumpkg.py", line 1427
        if (version := kwargs.get("version")) is not None:
                    ^
    SyntaxError: invalid syntax

This is my proposed fix to get it working again:

-    if (version := kwargs.get("version")) is not None:
-        kwargs["version"] = str(version)
+    if kwargs.get("version") is not None:
+        kwargs["version"] = str(kwargs["version"])

Versions Report

salt --versions-report

Salt Version:
          Salt: 3006.9

Python Version:
        Python: 3.10.14 (main, Jun 26 2024, 11:44:37) [GCC 11.2.0]

Dependency Versions:
          cffi: 1.14.6
      cherrypy: unknown
  cryptography: 42.0.5
      dateutil: 2.8.1
     docker-py: Not Installed
         gitdb: Not Installed
     gitpython: Not Installed
        Jinja2: 3.1.4
       libgit2: Not Installed
  looseversion: 1.0.2
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.2
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     packaging: 22.0
     pycparser: 2.21
      pycrypto: Not Installed
  pycryptodome: 3.19.1
        pygit2: Not Installed
  python-gnupg: 0.4.8
        PyYAML: 6.0.1
         PyZMQ: 23.2.0
        relenv: 0.17.0
         smmap: Not Installed
       timelib: 0.2.4
       Tornado: 4.5.3
           ZMQ: 4.3.4

System Versions:
          dist: ubuntu 22.04.5 jammy
        locale: utf-8
       machine: x86_64
       release: 5.15.0-130-generic
        system: Linux
       version: Ubuntu 22.04.5 jammy