Not a valid legacy git-crypt key file- attempt to decrypt

Hi folks,
Thanks for the work on this repo.

I am trying to convert my old git-crypt keys into new ones.
When I run "git-crypt unlock ../gpg-keys" it responds with
`Error: ../gpg-keys: not a valid git-crypt key file. If this key was created prior to git-crypt 0.4, you need to migrate it`

When I run `git-crypt migrate-key /path/to/old_key /path/to/migrated_key` it says:
`not a valid legacy git-crypt key file`.

I pretty urgently need to decrypt these files. Can anyone advise

## Contents of git-crypt-keys (my zip)
```
openpgp-revovs.d/
private-keys.v1.d/
pubring.kbx
random_seed
sshcontrol
trustdb.gpg
```