v2: Invalid URLs in manifest

[cschol]

In preparation for v2 integration I am running integration tests on select plugins.

[Stoermelder-P1] Validating plugin.json...
Exception validating URL: https://github.com/stoermelder/vcvrack-packone/blob/v2/README.md (HTTP Error 404: Not Found)
                                                                             
Exception validating URL: https://github.com/stoermelder/vcvrack-packone/blob/v2/CHANGELOG.md (HTTP Error 404: Not Found)
FAILED     
[Stoermelder-P1] Issues found in `plugin.json`:
                                                                             
Invalid URL: https://github.com/stoermelder/vcvrack-packone/blob/v2/README.md 
Invalid URL: https://github.com/stoermelder/vcvrack-packone/blob/v2/CHANGELOG.md