[WARNING] Do not manually upgrade to ExifTool 12.26 or later

[Mario]

These ExifTool versions introduce breaking changes. IMatch has to be updated as well to incorporate the new ExifTool namespaces.

I have done that already for the IMatch 2021 code base and it works just fine.
In case I ship another update for IMatch 2020 (unlikely), I will roll-down the required changes into the IMatch 2020 code base.