Update themes/theme_schema@0.0.1.json

I'm bad at this :D
Note: for some reason between different projects, background_fills look different...

themes/theme_schema@0.0.1.json

@@ -219,8 +219,8 @@
         "font": "'Source Sans Pro', 'ui-sans-serif', 'system-ui', sans-serif",
         "font_mono": "'Ubuntu Mono', 'ui-monospace', 'Consolas', monospace",
         "form_gap_width": "0px",
-        "input_background_fill": "*neutral_900",
-        "input_background_fill_dark": "*neutral_900",
+        "input_background_fill": "*neutral_800",
+        "input_background_fill_dark": "*neutral_800",
         "input_background_fill_focus": "*secondary_600",
         "input_background_fill_focus_dark": "*secondary_600",
         "input_background_fill_hover": "*input_background_fill",