postgresql compat: cast result from EXTRACT to INTEGER

postgresql compat: cast result from EXTRACT to INTEGER

Postgresql has changed the return type of the EXTRACT function to
numeric from float8 [0] in version 14, and I strongly assume that this
change is the reason why:
`SELECT EXTRACT (EPOCH FROM now());`
now returns a floating point instead of an integer value, which in
turn is not accepted in the prepared statements throughout our
codebase.

[0] https://www.postgresql.org/docs/release/14.0/

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>