ci: fix PATH

Author: Berrysoft

.github/workflows/libloading.yml

@@ -44,10 +44,10 @@ jobs:
           - i686-pc-windows-gnu
         include:
           - rust_target: x86_64-pc-windows-gnu
-            mingw_path: C:/M/mingw64/bin
+            mingw_path: C:\M\mingw64\bin
             package: mingw-w64-x86_64-gcc
           - rust_target: i686-pc-windows-gnu
-            mingw_path: C:/M/mingw32/bin
+            mingw_path: C:\M\mingw32\bin
             package: mingw-w64-i686-gcc
     steps:
       - uses: actions/checkout@v2
@@ -57,9 +57,10 @@ jobs:
       - uses: msys2/setup-msys2@v2
         with:
           install: ${{ matrix.package }}
-          update: true
-          location: C:/M
-      - run: msys2 -c "cargo test --target ${{ matrix.rust_target }}"
+          location: C:\M
+      - run: |
+          $env:PATH = "${{ matrix.mingw_path }};$env:PATH"
+          cargo test --target ${{ matrix.rust_target }}
         env:
           TARGET: ${{ matrix.rust_target }}