So it looks like some packages might be mentioned in the "depends=" of
other packages and marked as conflict, for example:
depends="!foo"
..and the conflicting package can be dropped from the repo entirely if
it is no longer needed, however the reference to it in `depends=` still
exists. This handles that situation by just ignoring the missing package
if it is only a conflicting dependency.
fixes https://gitlab.com/postmarketOS/pmaports/-/issues/1525