Shrink psycopg-pool to (0, 1) when cleaning connections

When min size is zero, max size must be greater than 0.

Closes #14795
(grafted from 357525621ea68bc99d688ddf04f9912905c9f3a0)

--HG--
branch : 8.0

trytond/trytond/backend/postgresql/database.py

@@ -221,7 +221,7 @@ class Database(DatabaseInterface):
             for database in list(databases.values()):
                 if ((now - database._last_use).total_seconds() > timeout
                         and database.name != name):
-                    database._connpool.resize(0, 0)
+                    database._connpool.resize(0, 1)
 
         if not (inst := databases.get(name)):
             with cls._lock: