bump release version to 4.0.0, and skip release of 3.0.0 version

At present, there is a difference between library major version (2) and
gir version (3). Due to the version mismatch, this commit skips release
of 3.0 version and bump release version to 4.0.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
22 files changed