Boundary check for pressure and p_tp.

[peterg1t]

Describe the bug
Pressure value was not in the allowed range (90,115)

To Reproduce
Steps to reproduce the behavior:

1. Run the test script with 89 kPa as a value for variable PRESS

Expected behavior
Pressure at our center hovers below the 90 kPa mark. This results in Ptp corrections larger than 1.1. This should be allowed as well (currently restricted to 0.9-1.1 range)

Screenshots

Additional context
Add any other context about the problem here.

[jrkerns]

Duplicate of #353 . See here for how to change it: https://pylinac.readthedocs.io/en/latest/calibration_docs.html#changing-a-bound

Edit: In your case you'd change the MIN_PRESSURE constant

[peterg1t]

Thanks James. Closing this now!