Deprecation date logic fix

[sophiewigmore]

Background

Recently we discovered the PHP dependency deprecation dates are all wrong because they are calculated based off of the patch version release-date, rather than the minor version line release date. We implemented #131 to resolve this on the singular dependency level for PHP.

On a larger scale, this may be an issue across our dependencies. We rely on the deprecation dates in our dependency metadata to make sure our buildpacks are only supporting secure and supported dependencies.

Issue

This issue is to assess if this is a problem across the repository, and if needed include a new GetDeprecationDate function to the dep_factory, or add some other mechanism to ensure our deprecation dates are calculated correctly. It would be ideal if we could standardize some portion of the code around the base-date we use to calculate the deprecation date in an effort to minimize additional technical debt we incur in the code base.