[bug] Incorrect display when change the unit by power and sqrt ...

[Routhleck]

import saiunit as u

x = 3. * u.meter
print(u.math.sqrt(x ** 2))
# 3. * meter2 ** 0.5

print((x ** 2) **(1/2))
# 3. * meter2 ** 0.5

print(((x ** 2) ** (1/2)) ** 2)
# 9. * metre ** 2.0