Bug 25285: Fix wrong message about required Koha version in plugins

Bug 25285: Fix wrong message about required Koha version in plugins

When you install a plugin that requires a newer Koha version, it reports
this:

<<
Warning: This report was written for a newer version of Koha. Run at your own risk.
>>

It is wrong in a couple ways:
- It is not a report.
- It feels like it dates back to when plugins were only run i.e.
  pre-hooks, etc.

This patch proposes a change to reflect this.

To test:
1. Verify the string changes make sense to you
2. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>