[faust2pdf] updated inkscape command line option

[LFSaw]

Inkscape version > (4035a4f, 2020-05-01) does not include -E option anymore, but uses -o instead.

[LFSaw]

I downloaded inkscape from their release page and used the binary found in Inkscape.app/Contents/MacOS.

from its man-page:

File export:
  -o, --export-filename=EXPORT-FILENAME      Output file name (file type is guessed from extension)

This version

$ ./inkscape --version
Inkscape 1.0 (4035a4f, 2020-05-01)
    Pango version: 1.43.0

does not include a -E option...

it also reads

Examples:
  Export input SVG (in.svg) to PDF (out.pdf) format:
	inkscape --export-filename=out.pdf in.svg
  Export input files (in1.svg, in2.svg) to PNG format keeping original name (in1.png, in2.png):
	inkscape --export-type=png in1.svg in2.svg

so maybe the long-form options --export-filename or --export-type are better options to keep compatibility?