Fix Windows Unit Test

[liu-shaojun]

Description

1. Why the change?

This submission is to fix https://github.com/intel-analytics/ipex-llm-workflow/actions/runs/10370306700/job/2873775018. The issue is that the ipex_llm module built in the previous step using shell: bash cannot be found in the step shell: powershell, the solution is to add the Python path to the PATH environment variable so that the module can be read in PowerShell.

Prepare all required actions
Run ./.github/actions/llm/cli-test-windows
Run llm-cli.ps1 -t $env:THREAD_NUM -n [2](https://github.com/intel-analytics/ipex-llm-workflow/actions/runs/10370306700/job/28737750187#step:12:2)56 -x llama -m $env:LLAMA_INT4_CKPT_PATH -p 'Once upon a time,'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'ipex_llm'
Split-Path : Cannot bind argument to parameter 'Path' because it is null.
At D:\actions-runner\ipex-llm-workflow-ut\_work\_tool\Python\3.11.9\x64\Scripts\llm-cli.ps1:1 char:32
+ ... -Path -Parent (python -c "import ipex_llm;print(ipex_llm.__file__)"))
+                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Split-Path], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.SplitPathCo 
   mmand

2. User API changes

3. Summary of the change

4. How to test?

• N/A
• Unit test: Please manually trigger the PR Validation here by inputting the PR number (e.g., 1234). And paste your action link here once it has been successfully finished.
• Application test
• Document test
• ...

5. New dependencies

• New Python dependencies
  - Dependency1
  - Dependency2
  - ...
• New Java/Scala dependencies and their license
  - Dependency1 and license1
  - Dependency2 and license2
  - ...