find out when procedure/function was changed for specific schema in postger

Question

I have DB with the multiple schemas, in one of the schemas someone changed the function, I am trying to find when it happens for that i am using the next query

select proname,oid, xmin,
'|||||||||', 
* 
from pg_catalog.pg_proc 
where proname = 'FUNCT_NAME'
order by xmin::text::int 
desc;

now I am facing the issue, I can't specify the schema name and cannot find how to convert xmin to the date-time. I was trying to use pg_xact_commit_timestamp(xmin) but it was disabled so I can get any info is there a way to check the date time when it was changed?