fix if the expected returned value was evaluated to false

[cle-b]

import lymbo
from lymbo import expected

@lymbo.test(expected=expected(False))
def return_false():
    return True

• before

** lymbo 0.3.0 (python 3.12.3) (Linux-6.11.0-26-generic-x86_64-with-glibc2.39) **
==== collecting tests
==== 1 test in 1 group
==== running tests
.P
==== tests executed in 0 second
==== results
- examples/simple.py::return_false() [PASSED]
==== 1 passed 

• after

** lymbo 0.3.1 (python 3.12.3) (Linux-6.11.0-26-generic-x86_64-with-glibc2.39) **
==== collecting tests
==== 1 test in 1 group
==== running tests
.F
==== tests executed in 0 second
==== results
- examples/simple.py::return_false()->(value=False) [FAILED]
==== 1 failed  
==== failures
examples/simple.py::return_false()->(value=False)
 - - - - reason:
  Expected value False, but got True.
  ---------------------
  The test has not been executed - [AssertionError: Expected value False, but got True.]
====