Stephen signed a one-year deal with the Jambos after leaving Hull City during the summer.
The 26-year-old left-back came through the youth system at Falkirk, making his first-team debut in 2011 aged only 16.
After making 100 appearances for the Bairns he made the switch to then English Premier League Swansea City in 2014.
He would go on to make 19 top team appearances in Wales before enjoying loan spells at Yeovil Town and Crewe Alexandra.
Capped for Scotland, Stephen joined Hull City for an undisclosed fee in 2017, where he made 46 appearances before leaving under freedom of contract this summer.