Exclude out-of-place keytype error raising from coverage
Exclude out-of-place keytype error raising from coverage

There's a redundant check in code it is not generally possible to
get to that tests supported key types. This is being retained to
guard against problems with future code changes, but the
error-raising clause is being excluded from coverage.

uptane/uptane,awwad/uptane,awwad/uptane,uptane/uptane