Do these everyday for a month and you will see a dramatic improvement in your squat.
Here is an outline of the movements. Do the movements in this order:
Walking ankle stretch - 2 minutes
Figure 4 march - 2 minutes
Side to side squat - 1 minute
Static ankle stretch - 4 minutes (1 minute per side x 4)
Static pigeon pose - 4 minutes (1 minute per side x 4)
Watch this video. It demonstrates the stretches outlined above.