Modify Renovate configuration to make maintenance easier

Lower maintenance burden (and adopters' impressions of projects) by auto-merging minor dependency upgrades OR ignore all but major version updates for dependencies. Pin all dependencies to avoid insecure updates for users and lower support requirements.

Advantages:
* fewer PRs means fewer build occurrences necessary
* easier to maintain
* PRs and issues from adopters addressed quicker
* consolidation of renovate configuration across project
* fewer minor versions (if just updating major versions)

Disadvantages:
* automated PR approval opens project to some security risk
* Many minor version updates increases maintenance burden of projects built using commitizen packages