fix: coerce condition predicate result to bool before comparing to target

[gaoflow]

Summary

Condition.check() used strict equality (==) to compare the predicate
return value against self.target (True or False). This silently
fails for any non-bool truthy or falsy value because Python's ==
operator only considers 0/False and 1/True as equal — all other
truthy/falsy values compare unequal:

'yes' == True   # False  ← should pass a conditions= callback
[1,2] == True   # False  ← should pass a conditions= callback
''    == False  # False  ← should pass an unless= callback
None  == False  # False  ← should pass an unless= callback

Reproducer:

from transitions import Machine

class Model:
    def my_cond(self):
        return "yes"   # truthy, non-bool

m = Model()
machine = Machine(model=m, states=["A", "B"],
                  transitions=[{"trigger": "go", "source": "A",
                                 "dest": "B", "conditions": "my_cond"}],
                  initial="A")
m.go()
print(m.state)   # prints 'A'  ← expected 'B'

Fix

Wrap the predicate result in bool() before the == self.target
comparison, matching how Python's if-statement handles truthiness.
The same bug was present in AsyncCondition.check().

All 71 existing tests pass.