Update GitHub Actions to use macos-latest and install mono

### Checklist

- [x] I confirm there are no unresolved issues reported on the [Chocolatey Status page](https://status.chocolatey.org).
- [x] I have verified this is the correct repository for opening this issue.
- [x] I have verified no other issues exist related to my problem.
- [x] I have verified this is not an issue for a specific package.
- [x] I have verified this issue is not security related.
- [x] I confirm I am using **official**, and **not** unofficial, or modified, Chocolatey products.

### What You Are Seeing?

Builds for MacOS were failing in GitHub Actions. As GitHub recently moved `macos-latest` to be `macos-15`, which drops `mono` from the build agent.

### What is Expected?

MacOS builds should work on `macos-latest`.

### How Did You Get This To Happen?

Just let GitHub Actions run for some PRs and other commits.

### System Details

GitHub Actions MacOS build.

### Installed Packages

```bash
N/A
```

### Output Log

```bash
N/A
```

### Additional Context

We have temporarily worked around this failure in 17682ea7232773b246ab4fe6f236f3d992e550dd by pinning to `macos-14`. This is not a complete fix as `macos-14` at some point will go away, and we should update to either `macos-15` or `macos-latest` before then.

Start by inspecting the GitHub Actions workflows responsible for the macOS build and review commit 17682ea7232773b246ab4fe6f236f3d992e550dd, which temporarily pins the runner to macos-14. Done means the macOS workflow runs successfully on macos-latest with mono available.

Written by the indexing model from the issue text.