Remove preferences dependency

It doesn't follow the Material Design spec, and usually required a
PreferencesService to be running. It is easier to just create our own
widgets.

lib/screens/settings_screen.dart

@@ -2,7 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:gitjournal/settings.dart';
 import 'package:gitjournal/utils.dart';
 
-import 'package:preferences/preferences.dart';
 import 'package:dynamic_theme/dynamic_theme.dart';
 
 class SettingsScreen extends StatelessWidget {
@@ -112,7 +111,7 @@ class SettingsListState extends State<SettingsList> {
 
     var brightness = DynamicTheme.of(context).brightness;
 
-    return PreferencePage([
+    return ListView(children: [
       SettingsHeader('Display Settings'),
       ListPreference(
         title: "Theme",

pubspec.lock

@@ -371,13 +371,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.4.0"
-  preferences:
-    dependency: "direct main"
-    description:
-      name: preferences
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "4.0.0"
   process:
     dependency: transitive
     description:

pubspec.yaml

@@ -25,7 +25,6 @@ dependencies:
   function_types: ^0.0.2
   auto_size_text: ^2.0.1
   fimber: ^0.3.0
-  preferences: ^4.0.0
   dynamic_theme: ^1.0.0
 
 dev_dependencies: