Resolve "Remove deprecations"

Closes #69 (closed)

lib/config/theme.dart

@@ -39,11 +39,9 @@ final ColorScheme lightColorScheme = ColorScheme.light(
   secondary: primarySwatch.shade500,
   onSecondary: Colors.white,
   error: errorColor,
-  background: textSwatch.shade200,
-  onBackground: textSwatch.shade500,
   onSurface: textSwatch.shade500,
   surface: textSwatch.shade50,
-  surfaceVariant: Colors.white,
+  surfaceContainerHighest: Colors.white,
   shadow: textSwatch.shade900.withOpacity(.1),
 );
 
@@ -52,11 +50,9 @@ final ColorScheme darkColorScheme = ColorScheme.dark(
   secondary: primarySwatch.shade500,
   onSecondary: Colors.white,
   error: errorColor,
-  background: const Color(0xFF171724),
-  onBackground: textSwatch.shade400,
   onSurface: textSwatch.shade300,
   surface: const Color(0xFF262630),
-  surfaceVariant: const Color(0xFF282832),
+  surfaceContainerHighest: const Color(0xFF282832),
   shadow: textSwatch.shade900.withOpacity(.2),
 );