Bug 27210: Typo in patron-attr-types.tt

Bug 27210: Typo in patron-attr-types.tt

Test Plan:
1. Make sure the ExtendedPatronAttributes syspref is active
2. Go to Administration > Patron attribute types
3. Click New patron attribute type
4. Check the sentence next to the Editable in OPAC checkbox (Should say
        "Requires above, does not work during self-registration if
        PatronSelfRegistrationVerifyByEmail if set." - Notice the use of
        'if set')
5. Apply Patch
6. Repeat steps 2-4 (Should now say "Requires above, does not work
        during self-registration if PatronSelfRegistrationVerifyByEmail
        is set." - Notice the use of 'is set')
7. If it says 'is set', the patch works as expected.

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>