[mnt] ignore contrib by bots in release notes + use miniforge3 in circleci

[yunjunz]

Description of proposed changes

• ignore contributions by bots in release notes via .github/release.yml file (Ignore contributions by bots in release notes isce-framework/snaphu-py#29)

• circleci: replace mambaforge with miniforge3

• timeseries2velocity.py --uncertainty: more comments and references

Reminders

• Pass Pre-commit check (green)
• Pass Codacy code review (green)
• Pass Circle CI test (green)
• Make sure that your code follows our style. Use the other functions/files as a basis.
• If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.