delete unused file

lib/ui/common/only_outer_shadow.dart

@@ -1,32 +0,0 @@
-import 'package:flutter/material.dart';
-
-class OnlyOuterShadow extends BoxShadow {
-  final BlurStyle blurStyle;
-
-  const OnlyOuterShadow({
-    Color color = const Color(0xFF000000),
-    Offset offset = Offset.zero,
-    double blurRadius = 0.0,
-    double spreadRadius = 0.0,
-    this.blurStyle = BlurStyle.normal,
-  }) : super(
-          color: color,
-          offset: offset,
-          blurRadius: blurRadius,
-          spreadRadius: spreadRadius,
-        );
-
-  @override
-  Paint toPaint() {
-    final Paint result = Paint()
-      ..color = color
-      ..maskFilter = MaskFilter.blur(this.blurStyle, blurSigma);
-    assert(
-      () {
-        if (debugDisableShadows) result.maskFilter = null;
-        return true;
-      }(),
-    );
-    return result;
-  }
-}