fix fftw install action

Author: mohawk2

github-actions/install-dep-fftw3/action.yml

@@ -5,6 +5,7 @@ runs:
     - name: Install FFTW3 (via apt-get)
       shell: bash
       if: runner.os == 'Linux'
+      run: |
           echo "::group::Install FFTW3 (via apt-get)"
           sudo apt-get -y update && sudo apt-get install --no-install-recommends -y libfftw3-dev
           echo "::endgroup::"