Format code with black and autopep8

This commit fixes the style issues introduced in 523d969 according to the output
from black and autopep8.

Details: https://deepsource.io/gh/GradienceTeam/Gradience/transform/841afc06-f1ac-4d2d-8811-c885c08cda80/

Author: deepsource-autofix[bot]

gradience/window.py

@@ -132,7 +132,7 @@ def setup_monet_page(self):
         self.monet_pref_group.set_title(_("Monet Engine"))
         self.monet_pref_group.set_description(
             _(
-                "Monet is an engine that generates a Material Design 3 " \
+                "Monet is an engine that generates a Material Design 3 "
                 "palette from an image's color."
             )
         )
@@ -269,10 +269,10 @@ def setup_colors_page(self):
         palette_pref_group.set_title(_("Palette Colors"))
         palette_pref_group.set_description(
             _(
-                'Named palette colors used by some applications. Default ' \
-                'colors follow the ' \
-                '<a href="https://developer.gnome.org/hig/reference/palette.html">'\
-                    'GNOME Human Interface Guidelines</a>.'
+                "Named palette colors used by some applications. Default "
+                "colors follow the "
+                '<a href="https://developer.gnome.org/hig/reference/palette.html">'
+                "GNOME Human Interface Guidelines</a>."
             )
         )
         for color in settings_schema["palette"]: