[Image] Bump mooncake version to v0.3.8.post1 (#6428)

### What this PR does / why we need it?
This patch bump the mooncake version to the latest
[release](https://github.com/kvcache-ai/Mooncake/releases/tag/v0.3.8.post1)
### Does this PR introduce _any_ user-facing change?

### How was this patch tested?
test is locally
>>> from mooncake.engine import TransferEngine
- vLLM version: v0.14.1
- vLLM main:
dc917cceb8

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

.github/workflows/schedule_image_build_and_push.yaml

@@ -17,6 +17,10 @@ on:
   push:
     tags:
       - 'v*'
+  pull_request: 
+    branches:
+      - 'main'
+    types: [ labeled, synchronize ]
   workflow_dispatch:
     inputs:
       tag:
@@ -33,6 +37,7 @@ on:
 jobs:
   image_build:
     name: Image Build and Push
+    if: ${{ github.event_name != 'pull_request' || contains(github.event.pull_request.labels.*.name, 'image-build')  }}
     strategy:
       matrix:
         build_meta:
@@ -59,7 +64,7 @@ jobs:
       dockerfile: ${{ matrix.build_meta.dockerfile }}
       suffix: ${{ matrix.build_meta.suffix }}
       quay_username: ${{ vars.QUAY_USERNAME }}
-      should_push: ${{ github.repository_owner == 'vllm-project' }}
+      should_push: ${{ github.repository_owner == 'vllm-project' && (github.event_name != 'pull_request') }}
       workflow_dispatch_tag: ${{ inputs.tag }}
     secrets:
       QUAY_PASSWORD: ${{ secrets.QUAY_PASSWORD }}