fix(build): change shell to cmd for llama.cpp build on windows-gpu

Author: Gioee

.github/workflows/main.yml

@@ -392,10 +392,11 @@ jobs:
             ls -la build/llama.cpp/bin/
           fi
 
-      - name: build llama.cpp main library (mingw)
+      - name: build llama.cpp main library (msvc)
         if: matrix.name == 'windows-gpu' && steps.cache-llama.outputs.cache-hit != 'true'
-        shell: msys2 {0}
+        shell: cmd
         run: |
+          call "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvarsall.bat" x64
           make build/llama.cpp.stamp ${{ matrix.make }} LLAMA_ARGS="--target common"
           make build/llama.cpp.stamp ${{ matrix.make }} LLAMA_ARGS="--target llama"
           make build/llama.cpp.stamp ${{ matrix.make }} LLAMA_ARGS="--target ggml"