defaultHackageSecurityConfig inconsistent with FromJSON instance for HackageSecurityConfig

[mpilgrem]

From pantry-0.1.1.0, the FromJSON instance for WithJSONWarnings HackageSecurityConfig has included:

hscIgnoreExpiry <- o ..:? "ignore-expiry" ..!= True

However, inconsistently, the defaultHackageSecurityConfig has remained including:

, hscIgnoreExpiry = False

I think the default should be be changed to be consistent with the changed approach to the FromJSON instance. I will raise a pull request accordingly.