I’m running Mac OS 11.5.2 (Big Sur). I have the following version of unison installed using

```
brew install unison

```

Which is

```
$ unison -version
unison version 2.51.4 (ocaml 4.12.0)

```

However, in order to work with a virtual Ubuntu box, which runs

```
$ unison -version
unison version 2.51.2 (ocaml 4.08.1)

```

I need to downgrade my Mac OS version of Unison. But the brew command doesn’t give me control over the version. How do I downgrade my Mac version to match the Linux version?