add MPL-2.0-no-copyleft-exception to the allow list (#8194)
### Description
In this PR https://github.com/vercel/turbo/pull/8174 the library prehash
is licensed using MPL2.0 (great) but without the copyleft exception.
I believe that we are OK. From what I understand this prevents us from
making and redistributing changes to this library under one of the MPL
secondary licenses ("Secondary License" means either the GNU General
Public License, Version 2.0, the GNU Lesser General Public License,
Version 2.1, the GNU Affero General Public License, Version 3.0, or any
later versions of those licenses).
It does not exclude us from using that library in a 'larger work' that
is licensed using a different (compatible) license so for the purpose of
distributing a binary it is the same as MPL-2.0
### Testing Instructions
N/A
