[GNC] Release Next Weekend, please test nightly builds

[John Ralls]

Dear Users,

With a week to go until the 5.7 release we'd be overjoyed to have some brave users give the nightly builds a spin:
https://code.gnucash.org/builds/win32/stable and https://code.gnucash.org/builds/flatpak/stable.

Please test on a *copy* of your data file! 

For German FinTS users: Nightly builds beginning with today's have the latest beta release of AQBanking, version 6.5.11beta. This fixes failures in the last release version (6.5.4) so if no one reports any serious problems we'll break our usual policy and include it in the 5.7 release bundles. 

Thanks!

Regards,
John Ralls