libreofficekit: update lloconv git URL

Change-Id: I3a1699efe5335c43f79a15c3487f8deb7d1be5c6
Reviewed-on: https://gerrit.libreoffice.org/59635
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

libreofficekit/README

@@ -21,7 +21,7 @@ LibreOfficeKitInit.h for you.
 functionality as in LibreOfficeKit.h.)
 
 An example program can be seen on:
-https://github.com/ojwb/lloconv
+https://gitlab.com/ojwb/lloconv
 
 Tiled Rendering
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