Use floats for all EGS values - #642

Description

The API returns floats not ints for the gas values. This also adds an error log if fetching or parsing fails to make sure it's clear to the operator.

Related Issue Or Context

Closes: #

How Has This Been Tested? Testing details.

Updated existing test to use a float. Tested it against the actual live endpoint locally.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation

Checklist:

• I have commented my code, particularly in hard-to-understand areas.
• I have ensured that all acceptance criteria (or expected behavior) from issue are met
• I have updated the documentation locally and in chainbridge-docs.
• I have added tests to cover my changes.
• I have ensured that all the checks are passing and green, I've signed the CLA bot