Spec: Set the python version explicitly to 3.9

The __python3 macro defaults to /usr/bin/python3. This is not a problem
as long as the python3 symlink always points to the python3.9 runtime.
If that is changed via alternatives or another means, the following
error is returned:

  Traceback (most recent call last):
    File "/usr/bin/dnf", line 61, in <module>
      from dnf.cli import main
  ModuleNotFoundError: No module named 'dnf'

This update specifically sets the __python3 macro to /usr/bin/python3.9
which results in the following shebang within /usr/bin/dnf:

  #!/usr/bin/python3.9

Resolves: rhbz#2211019

Signed-off-by: Kyle Walker <kwalker@redhat.com>

dnf.spec

@@ -56,6 +56,9 @@
 
 %global py3pluginpath %{python3_sitelib}/%{name}-plugins
 
+# To avoid breakage if the python3 symlink is changed
+%{?python3_version:%global __python3 /usr/bin/python%{python3_version}}
+
 # Use the same directory of the main package for subpackage licence and docs
 %global _docdir_fmt %{name}
 
@@ -66,7 +69,7 @@ It supports RPMs, modules and comps groups & environments.
 
 Name:           dnf
 Version:        4.14.0
-Release:        6%{?dist}
+Release:        7%{?dist}
 Summary:        %{pkg_summary}
 # For a breakdown of the licensing, see PACKAGE-LICENSING
 License:        GPLv2+
@@ -369,6 +372,9 @@ popd
 %{python3_sitelib}/%{name}/automatic/
 
 %changelog
+* Tue May 30 2023 Kyle Walker <kwalker@redhat.com> - 4.14.0-7
+- Explicitly use the python3.9 runtime (RhBug:2211019)
+
 * Thu May 11 2023 Jaroslav Rohel <jrohel@redhat.com> - 4.14.0-6
 - Add reboot option to DNF Automatic (RhBug:2124793)
 - Omit src RPMs from check-update (RhBug:2151910,2203069)