Fix addition/deletion of namespaces and exception on startup

[VelorumS]

Fix exception in startup_fn() because of no namespace name in clustersecrets metadata.

Fix exception in on_field_data() when encountering a deleted namespace.

Fix cache update in on_field_data() so a newly added namespaces could get an up-to-date secret data.

Fix the addition of new namespaces to the list for synchronization.

Fix storing body in cache so the new namespaces could get the data.

Fix storing clustersecret's namespace name in cache in create_fn().

Update kopf to fix mutable default <class 'kopf._cogs.structs.diffs.Diff'> for field diff is not allowed: use default_factory with Python 3.11+.

Fixes #117
Fixes #116

[zakkg3]

I have to fix the e2e test and if that passes ill merge this. I guess in the next days I hope I find the time for this.
sorry for the delay.