Bump Log::Any minimum version from 0 to 0.15

Today I was working on a repo with an older version of Log::Any
installed, but no Log::Any::Adapter.  I was unable to get
Log::Any::Adapter installed until I bumped Log::Any from 0.14 to 0.15 on
my end.  So, I think bumping the version makes sense.  Since it actually
has no deps, this shouldn't be a blocker to anyone upgrading.

Closes #40