Update write_repodata(...) to be compatible with newer conda versions

[dbast]

Checklist

• I added a descriptive title
• I searched open requests and couldn't find a duplicate

What is the idea?

write_repodata(...) is currently accessing private fields in the repodata that got removed by conda 23.1.0, see also discussion here #627

there are potentially two options to move forward:

• conda provides a public API to access the repop data (requires implementation on conda side with releases + constructor update with release)
• or the entire constructor def write_repodata(...) function is replaced by a conda-index call against a local folder with all the packages that are shipped by the installer (potentially only requires a constructror update without conda or conda-index changes) ... do be checked if this is possible

Why is this needed?

.

What should happen?

.

Additional Context

.