workflows: fix client workflow to use bash by default on windows

.github/workflows/client.yml

@@ -20,6 +20,9 @@ jobs:
       TARGET_ARCH: "${{ matrix.arch }}"
     runs-on: "${{ matrix.os.on }}"
     name: build ${{ matrix.os.name }}-${{ matrix.arch }}
+    defaults:
+      run:
+        shell: bash
     steps:
     - uses: actions/checkout@v4
     - uses: dtolnay/rust-toolchain@stable