There is a topic that includes a download link for 4.A.0013.4, but that would be a fastboot installation from a computer to your FP3, and frankly I am out of the loop right now how that exactly works and how it affects existing data on your phone. The file can not be just downloaded to the phone and be installed from there – that will just not work.
There is no way to install a version other than the most recent one OTA.
P.S.: I’m just noticing Fairphone also currently offers the penultimate update 4.A.0013.4 for manual installation (fastboot):