package/cog: bump to version 0.4.0

package/cog: bump to version 0.4.0

This is a new major release, to be used along with WPE WebKit 2.26.0
as per the compatibility matrix:

  https://wpewebkit.org/release/schedule/#compatible-components

The release includes experimental support for DRM/KMS output, which is
explicitly disabled at the moment. The complete release notes are
available at:

  https://wpewebkit.org/release/cog-0.4.0.html

Starting with the 0.4.x series, Cog is available directly from the
main WPE WebKit site, and this COG_SITE is changd accordingly.

Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>