This PR fixes issues with credential registries

[pfeairheller]

This PR fixes the following issues with credential registries:

• https://github.com/WebOfTrust/keria/issues/147
• https://github.com/WebOfTrust/keria/issues/146
• https://github.com/WebOfTrust/keria/issues/148

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 97.14286% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 92.97%. Comparing base (c1b638c) to head (90f940d).

Files	Patch %	Lines
src/keria/core/longrunning.py	85.71%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #197 +/- ## ========================================== + Coverage 92.72% 92.97% +0.25% ========================================== Files 38 38 Lines 6597 6647 +50 ========================================== + Hits 6117 6180 +63 + Misses 480 467 -13 ```

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