pdfcpu: Use a grep-less version parts identification

  # `versionCheckHook` uses --ignore-environment

  installCheckPhase = ''

    echo checking the version print of pdfcpu

    $out/bin/pdfcpu version | grep ${version}

    $out/bin/pdfcpu version | grep -q $(cat COMMIT | cut -c1-8)

    $out/bin/pdfcpu version | grep -q $(cat SOURCE_DATE)

    versionOutput="$($out/bin/pdfcpu version)"

    for part in ${version} $(cat COMMIT | cut -c1-8) $(cat SOURCE_DATE); do

      if [[ ! "$versionOutput" =~ "$part" ]]; then

          echo version output did not contain expected part $part . Output was:

          echo "$versionOutput"

          exit 3

      fi

    done

  '';

  subPackages = [ "cmd/pdfcpu" ];