wallpaper_page: remove `const` from non const constructor

[Jupi007]

[{
	"resource": "/home/jupiter007/Flutter/settings/lib/view/pages/wallpaper/wallpaper_page.dart",
	"owner": "_generated_diagnostic_collection_name_#1",
	"code": {
		"value": "const_with_non_const",
		"target": {
			"$mid": 1,
			"external": "https://dart.dev/diagnostics/const_with_non_const",
			"path": "/diagnostics/const_with_non_const",
			"scheme": "https",
			"authority": "dart.dev"
		}
	},
	"severity": 8,
	"message": "The constructor being called isn't a const constructor.\nTry removing 'const' from the constructor invocation.",
	"source": "dart",
	"startLineNumber": 213,
	"startColumn": 15,
	"endLineNumber": 213,
	"endColumn": 20
}]

[Jupi007]

Thanks @Feichtmeier, I had forgotten this :)