contains? for continuous intervals fails to contain same points when a inclusive b exclusive

reproduce with

```elixir
refute Interval.contains?(
         FloatInterval.new(left: 1.0, right: 4.0, bounds: "()"),
         FloatInterval.new(left: 1.0, right: 4.0, bounds: "[]")
       )

assert Interval.contains?(
         FloatInterval.new(left: 1.0, right: 4.0, bounds: "[]"),
         FloatInterval.new(left: 1.0, right: 4.0, bounds: "()")
       )
```