Add @regex directive

[jgorgel]

get /api/validate_phone {
    query {
        """Phone number validation (XXX-XXX-XXXX format)"""
        @regex(pattern="^\d{3}-\d{3}-\d{4}$")
        phone: str
    }
    
    return { "valid": true };
}

[Folyd]

LGTM, thanks.