This update for inkscape fixes the following issue:

- Remove inkscape-extension-skencil completely for Leap 15.2 by now. (jsc#SLE-12254, bsc#1171258)
The extension was built only on openSUSE in the past, nowadays:
* Tumbleweed does not build it since skencil does not support python 3.
* SLE has never built and shipped the extension.
Hence this submission actually disables the extension on Leap 15.2 and above to keep
it consistent with SLE and TW. The stub for packaging the extension is still kept in the spec
for future needs when we bring skencil back to the release.