Verify Slider.value limits

[ndonkoHenri]

Close #1052

Test Code:
The main issue is resolved: slider.value now prints 100 (the max)

>>> import flet as ft
>>> slider = ft.Slider(divisions=100, value=150, min=0, max=100)
>>> slider.value
100

# but :

>>> repr(slider)
'Slider(value=150, min=0, max=100, divisions=100)'

Important Note:
As seen above the __repr__ or even __str__ still has value=150.
This is because the self.__attrs (where the props are stored) is not updated.

This could be solved by adding self.value = v (resetting the value / updating the self.__attrs) when verifying the limits in the value @property as follows:

@property
def value(self) -> OptionalNumber:
    v = self._get_attr("value", data_type="float")
    # verify limits
    if v < self.min:
        v = self.min
        self.value = v
    elif v > self.max:
        v = self.max
        self.value = v

    return v

but because we are in the @property, it will only be applied when slider.value is called.

>>> import flet as ft
>>> slider = ft.Slider(divisions=100, value=150, min=0, max=100)
>>> repr(slider)
'Slider(value=150, min=0, max=100, divisions=100)'
>>> slider.value
100
>>> repr(slider)
'Slider(value=100, min=0, max=100, divisions=100)'

Let me have your thoughts on the importance of this.