Allow %py3_shebang_fix macro to add -P argument to shebang lines

There was a bug in dnf and dnf-automatic that caused traceback
when running the Python interpreter with the `-P` argument.
Since the bug has been fixed, the `-P` argument can be used.

dnf.spec

@@ -257,10 +257,6 @@ rm %{buildroot}%{_mandir}/man5/%{name}.conf.5*
 %endif
 
 %if 0%{?fedora} >= 41 || 0%{?rhel} >= 10
-# Don't add -P to Python shebangs
-# The executable Python scripts import each other
-%undefine _py3_shebang_P
-
 %py3_shebang_fix %{buildroot}%{_bindir}/dnf-3
 %py3_shebang_fix %{buildroot}%{_bindir}/dnf-automatic
 %py3_shebang_fix %{buildroot}%{python3_sitelib}/%{name}/cli/completion_helper.py