ci: removed bash shell from steps in Windows build job

.github/workflows/nightly-builds.yml

@@ -36,9 +36,6 @@ jobs:
         uses: seanmiddleditch/gha-setup-ninja@v4
 
       - name: Configure CMake
-        # Use a bash shell so we can use the same syntax for environment variable
-        # access regardless of the host operating system
-        shell: bash
         working-directory: ${{github.workspace}}/build
         # Note the current convention is to use the -S and -B options here to specify source
         # and build directories, but this is only available with CMake 3.13 and higher.
@@ -47,7 +44,6 @@ jobs:
 
       - name: Build
         working-directory: ${{github.workspace}}/build
-        shell: bash
         # Execute the build. You can specify a specific target with "--target <NAME>"
         run: cmake --build . --config ${{ matrix.build_conf }} --parallel 8