Fix issue with AssetAmountInput validation happening too early

Was due to Textual changed behaviour

In 0.53.0 this change caused that:
BREAKING: for many widgets, messages are now sent when programmatic changes that mirror user input are made #4256

And with 0.56.0 this fix is available.
See also: Textualize/textual#4392

clive/__private/ui/widgets/inputs/asset_amount_base_input.py

@@ -71,7 +71,8 @@ def __init__(
         ----
         placeholder: If not provided, placeholder will be dynamically generated based on the asset type.
         """
-        self._currency_selector: CurrencySelectorBase[AssetInputT] = self.create_currency_selector()
+        with self.prevent(CurrencySelectorBase.Changed):
+            self._currency_selector: CurrencySelectorBase[AssetInputT] = self.create_currency_selector()
         default_asset_type = self._currency_selector.default_asset_cls
         default_asset_precision = Asset.get_precision(default_asset_type)