Bug 30128: Change language_subtag_registry.description to varchar(255)

Bug 30128: Change language_subtag_registry.description to varchar(255)

In database, language_descriptions.description is VARCHAR(255).
language_subtag_registry.description is VARCH(25), it should have same size.

You can see in https://www.loc.gov/standards/iso639-2/php/code_list.php there is for example 'South American Indian languages'

Test plan :
1) Run atomic update
2) Check language_subtag_registry.description is now varchar(255)

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>