fix build by allowing older ddbc

[John-Colvin]

or alternatively find a way to manually update code.dlang.org to recognise ddbc-0.3.8, because currently it only sees 0.3.7. See also dlang/dub-registry#338

Also, is it necessary to be so strict with the version and update it? dub will get the most recent that meets the spec, so unless the old version doesn't work then there's no need to update it in the dub.sdl, you're just forcing people to upgrade who might have a reason not to.

If you do merge this PR, please make a patch release so other people can use it.

[SingingBush]

ddbc 0.3.7 has problems with recent compilers, that was reason for the 0.3.8 release. Since that last ddbc tag a minor breaking change was merged so the next ddbc should be 0.4.0 to prevent use of ~>0.3.8 being an issue and allow the possibility of further 0.3.* versions as well as newer 0.4.* releases. Until ddbc 0.3.8 is available in code.dlang then there's not much point doing anything with hibernated.