Update the changelog for version 1.2.5

[bhazelton]

Description

Create a new release now that we've merged #424, fixing a major bug.

Motivation and Context

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Reference simulation update or replacement
• [ ] Documentation change (documentation changes only)
• [x] Version change
• [ ] Build or continuous integration change

Checklist:

For all pull requests:

• [x] I have read the contribution guide.
• [x] My code follows the code style of this project.

Version change checklist:

• [x] I have updated the CHANGELOG to put all the unreleased changes under the new version (leaving the unreleased section empty).
• [ ] I have run the appropriate tests for this level of version change (described in the readme under versioning).

We are in a state currently where the reference sims need to be updated, but the unit tests pass and we are confident that the bug fix in #424 is correct and critical.

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e369f72) 99.20% compared to head (aed0910) 99.20%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #425 +/- ## ======================================= Coverage 99.20% 99.20% ======================================= Files 13 13 Lines 2256 2256 ======================================= Hits 2238 2238 Misses 18 18 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RadioAstronomySoftwareGroup). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RadioAstronomySoftwareGroup)

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