Previously, when translating `Exif.CanonCs.LensType`,
`Exif.CanonCs.MaxAperture` was used as the upper bound to find a
potential match. In Exiv2#2057, the test file produced a value outside of
that range and the lens was not identified.

The fix uses `Exif.CanonCs.MinAperture` instead.

This reverts commit d8d5a3a.

Revert to fix the lens detection in a different way.

The `Canon RF 24-105 F4-7.1 IS STM` lens is reported as using an
`Exif.CanonCs.MaxAperture` of `F7.3` instead of `F7.1`. As a result,
the translation of `Exif.CanonCs.LensType` is missing.

Fix updates the `CanonEV()` decode function to provide the correct
value.