Use expectation line number in failure output
When an example fails, the source location is displayed.
1) Spectator::Wrapper stores a value
Failure: wrapper.get(Int32) does not equal 24
actual: 42
expected: 24
# spec/spectator/wrapper_spec.cr:4 <=== This location.
Currently, the line number reported is the line number the example starts on. I think it would be beneficial to change this to the line number of the failed expectation.