Postgresql python in upgraded version 16.2

Hello all,

I upgraded version of Postgres from 13.5 to newest 16.2. But Python was not upgraded.

I create procedure pyver():

CREATE OR REPLACE FUNCTION pyver ()

 RETURNS TEXT

 AS $$

     import sys

     pyversion = sys.version

     return pyversion

 $$ LANGUAGE 'plpython3u';

On the Postgres 13.5 I get this result:

# psql -d database

psql (13.5)

Type "help" for help.

postgres@database # select pyver();

postgres@database #

On the Postgres 16.2 (upgraded from version 13.5) I get this result:

# psql -d database

database=# select pyver();

database=#

It seems python was not upgraded when I upgrade PostgreSQL. Is possible upgrade the python to actual version 3.9.x installed on RedHat 8.5 ?

Thanks 

Michal