wendelin.core: v↑ 2.0.alpha3 -> 2.0.alpha3.post7

Hello Kirill,

Since the wendelin.core 2.alpha3 release 9 month ago, new fixes were added to wendelin.core, which we would like to have in SlapOS. One very important new feature is that this wendelin.core version now support golang 1.20, so with this we can easily proceed to upgrade our default golang version.

I run integration tests, some tests fail, but all of them seem to also fail on the master branch, so I believe this should be ok to merge.

Best, Levin

/cc @kirr