boolen coercion doesn't work well with perl v5.40 and above

Here's a script that claims a valid object is invalid. As you can see, I'm using perl's native booleans:

```perl
use v5.42;
use JSON::Validator;

my $jv = JSON::Validator->new;
$jv->coerce('booleans');
$jv->schema({
type => 'object',
properties => {
v => {
type => 'boolean',
const => true,
}
}
});
my @errors = $jv->validate({ v => 1 });
say foreach @errors;
say 'ALL OK' if ! @errors;
```

Same thing happens if I replace `const => true` with `enum => [true]`.

Also `true` doesn't validate against `const => true`, when booleans are coerced.