app-office/gnucash: Bump to 3.8b

app-office/gnucash: Bump to 3.8b

Bump to EAPI 7. Switch to ninja to run tests instead of GNU make.

Install example files into their own directory.

No longer install redundant license file. This also prevents a sandbox
violation.

Because net-libs/aqbanking dropped the gtk USE flag, we've increased the version
requirement, and trigger the gtk USE flag on sys-libs/gwenhywfar directly. Also,
make the >dev-libs/libofx dependent on the subslot as well.

Bug: https://bugs.gentoo.org/714920
Bug: https://bugs.gentoo.org/704632
Bug: https://bugs.gentoo.org/692626

Package-Manager: Portage-2.3.89, Repoman-2.3.20
Signed-off-by: Aaron W. Swenson <titanofold@gentoo.org>