fix: flagsmith string to double conversion issue(#1557)

[kushbatra]

This PR

This PR fixes the issue where FlagsmithProvider.getDoubleDetails fails to parse flag values returned as strings (e.g., "42.42") from Flagsmith. Previously, the provider expected a java.lang.Double and returned an error if the value was a string. With this change, the provider will attempt to parse string values to Double when evaluating double flags, ensuring compatibility with Flagsmith environments that store numeric values as strings. Similar case is handled for Integer as well.

Related Issues

Fixes #1557

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