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 :)