pgsql: Fix Python deprecation warning

Fix Python deprecation warning

Starting with Python 3.14, contrib/unaccent/generate_unaccent_rules.py
complains

    DeprecationWarning: codecs.open() is deprecated. Use open() instead.

This makes that change.  This works for all Python 3.x versions.

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/2a668979-ed92-49a3-abf9-a3ec2d460ec2%40eisentraut.org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/16686a853f1b0f479fbe716acecb3a264e70c824

Modified Files
--------------
contrib/unaccent/generate_unaccent_rules.py | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)