i think is 1.15 but not dev, because i see new map and is installed from

sudo apt-get update && sudo apt-get install dump1090-mutability -y

from my own tutorial ( now i am copying many of the info you have)

pi@raspberrypi:~ $ dump1090-mutability
Tue Aug 20 22:19:11 2019 BST EB_SOURCE EB_VERSION starting up.