Bumping the version of libgda to 4.1.5

[Kjartan Maraas <kmaraas broadpark no>]

Hi.

Bumped into a problem with the current libgda version in jhbuild
breaking the build of anjuta.

Anjuta is depending on GDA_CONNECTION_OPTIONS_THREAD_SAFE enum member
that's only available in the 4.1.x series afaics. Would it be ok to use
the newer version in the 2.31.x/3.0 series?

Cheers
Kjartan