v2.6.0 Changelog

[ShockwaveNN]

Hi, dependabot shown that there is a new version of `json library, but I think CHANGES.md file is missing any info about this release

[hsbt]

Unfortunately, there is no enough resource to maintain it for me. I did delete it from this repo at 739e064

[ShockwaveNN]

Are you sure this is a good idea? Maybe leave old CHANGES but make latest statement that There will be new lines in this CHANELOG due to low free time

[hsbt]

I always welcome your code and patch like #480