fix yumpkg for Python <3.8

Author: hurzhurz

changelog/67151.fixed.md

@@ -0,0 +1 @@
+Fix yumpkg module for Python<3.8

salt/modules/yumpkg.py

@@ -1425,8 +1425,8 @@ def install(
                 'version': '<new-version>',
                 'arch': '<new-arch>'}}}
     """
-    if (version := kwargs.get("version")) is not None:
-        kwargs["version"] = str(version)
+    if kwargs.get("version") is not None:
+        kwargs["version"] = str(kwargs["version"])
     options = _get_options(**kwargs)
 
     if salt.utils.data.is_true(refresh):