Fix mesh2_manual exapmle. (bevyengine#14831)

Fix `mesh2d_manual` example from changes in bevyengine#13069.

```
wgpu error: Validation Error

Caused by:
  In RenderPass::end
    In a set_pipeline command
      Render pipeline targets are incompatible with render pass
        Incompatible depth-stencil attachment format: the RenderPass uses a texture with format Some(Depth32Float) but the RenderPipeline with 'colored_mesh2d_pipeline' label uses an attachment with format None
```

examples/2d/mesh2d_manual.rs

@@ -7,7 +7,7 @@
 
 use bevy::{
     color::palettes::basic::YELLOW,
-    core_pipeline::core_2d::Transparent2d,
+    core_pipeline::core_2d::{Transparent2d, CORE_2D_DEPTH_FORMAT},
     math::FloatOrd,
     prelude::*,
     render::{
@@ -18,9 +18,10 @@ use bevy::{
             ViewSortedRenderPhases,
         },
         render_resource::{
-            BlendState, ColorTargetState, ColorWrites, Face, FragmentState, FrontFace,
-            MultisampleState, PipelineCache, PolygonMode, PrimitiveState, PrimitiveTopology,
-            RenderPipelineDescriptor, SpecializedRenderPipeline, SpecializedRenderPipelines,
+            BlendState, ColorTargetState, ColorWrites, CompareFunction, DepthBiasState,
+            DepthStencilState, Face, FragmentState, FrontFace, MultisampleState, PipelineCache,
+            PolygonMode, PrimitiveState, PrimitiveTopology, RenderPipelineDescriptor,
+            SpecializedRenderPipeline, SpecializedRenderPipelines, StencilFaceState, StencilState,
             TextureFormat, VertexBufferLayout, VertexFormat, VertexState, VertexStepMode,
         },
         texture::BevyDefault,
@@ -198,7 +199,22 @@ impl SpecializedRenderPipeline for ColoredMesh2dPipeline {
                 topology: key.primitive_topology(),
                 strip_index_format: None,
             },
-            depth_stencil: None,
+            depth_stencil: Some(DepthStencilState {
+                format: CORE_2D_DEPTH_FORMAT,
+                depth_write_enabled: false,
+                depth_compare: CompareFunction::GreaterEqual,
+                stencil: StencilState {
+                    front: StencilFaceState::IGNORE,
+                    back: StencilFaceState::IGNORE,
+                    read_mask: 0,
+                    write_mask: 0,
+                },
+                bias: DepthBiasState {
+                    constant: 0,
+                    slope_scale: 0.0,
+                    clamp: 0.0,
+                },
+            }),
             multisample: MultisampleState {
                 count: key.msaa_samples(),
                 mask: !0,