[Misc] Bump mooncake version to v0.3.8.post1 (#6110)

### What this PR does / why we need it?
Since the mooncake has the newer
[release](https://github.com/kvcache-ai/Mooncake/releases/tag/v0.3.8.post1),
we pin the tag to latest release

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.13.0
- vLLM main:
d68209402d

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

docs/source/tutorials/pd_colocated_mooncake_multi_instance.md

@@ -121,7 +121,7 @@ Moonshot AI. Installation and compilation guide:
 First, obtain the Mooncake project using the following command:
 
 ```bash
-git clone -b v0.3.7.post2 --depth 1 https://github.com/kvcache-ai/Mooncake.git
+git clone -b v0.3.8.post1 --depth 1 https://github.com/kvcache-ai/Mooncake.git
 cd Mooncake
 git submodule update --init --recursive
 ```

docs/source/tutorials/pd_disaggregation_mooncake_multi_node.md

@@ -177,7 +177,7 @@ Mooncake is the serving platform for Kimi, a leading LLM service provided by Moo
 First, we need to obtain the Mooncake project. Refer to the following command:
 
 ```shell
-git clone -b v0.3.7.post2 --depth 1 https://github.com/kvcache-ai/Mooncake.git
+git clone -b v0.3.8.post1 --depth 1 https://github.com/kvcache-ai/Mooncake.git
 ```
 
 (Optional) Replace go install url if the network is poor

docs/source/tutorials/pd_disaggregation_mooncake_single_node.md

@@ -98,7 +98,7 @@ Mooncake is the serving platform for Kimi, a leading LLM service provided by Moo
 First, we need to obtain the Mooncake project. Refer to the following command:
 
 ```shell
-git clone -b v0.3.7.post2 --depth 1 https://github.com/kvcache-ai/Mooncake.git
+git clone -b v0.3.8.post1 --depth 1 https://github.com/kvcache-ai/Mooncake.git
 ```
 
 (Optional) Replace go install url if the network is poor