python3Packages.pyqt6: fix support for dbus-python (#389179)

pkgs/development/python-modules/pyqt/6.x.nix

@@ -38,8 +38,7 @@ buildPythonPackage rec {
   patches = [
     # Fix some wrong assumptions by ./project.py
     # TODO: figure out how to send this upstream
-    # FIXME: make a version for PyQt6?
-    # ./pyqt5-fix-dbus-mainloop-support.patch
+    ./pyqt6-fix-dbus-mainloop-support.patch
     # confirm license when installing via pyqt6_sip
     ./pyqt5-confirm-license.patch
     # Fix build with Qt 6.8.2

pkgs/development/python-modules/pyqt/pyqt6-fix-dbus-mainloop-support.patch

@@ -0,0 +1,11 @@
+--- a/project.py
++++ b/project.py
+@@ -247,7 +247,7 @@
+         dbus_lib_dirs = []
+         dbus_libs = []
+ 
+-        args = ['pkg-config', '--cflags-only-I', '--libs dbus-1']
++        args = ['pkg-config', '--cflags-only-I', '--libs dbus-1', 'dbus-python']
+ 
+         for line in self.read_command_pipe(args, fatal=False):
+             for flag in line.strip().split():