CBMC should have a versioned brew tap

[danielsn]

Currently, the only version of CBMC available on brew is the latest. This makes it difficult for tools that wish to pin to particular versions. The supported path is to have a separate tap that allows versioned CBMC releases https://docs.brew.sh/Versions

This should not be difficult to maintain as part of the existing CBMC release process.

[tautschnig]

This has been addressed in #6817.