postgresql chart to v13.2.2, base to 2.1.0, renovate.json improvements

Closes #66 (closed)

This MR contains the following updates:

Package	Update	Change
postgresql (source)	patch	13.2.1 -> 13.2.2
registry1.dso.mil/ironbank/big-bang/base	patch	2.0.0 -> 2.1.0
registry1.dso.mil/ironbank/opensource/postgres/postgresql	patch	15.4 -> 15.5

This MR also contains some slight improvements to renovate.json:

• Automatically updates appVersion and - Confluence: lines in chart/Chart.yaml (similar to other packages)
• Automatically bumps changelog (similar to other packages), although didn't quite get this to work in my testing
• Ignores postgresql subchart updates - the Bitnami chart updates are too frequent and unimportant for a PoC/Dev/internal database. Postgres image updates are slightly more important, which will still be tracked.

All changes to the renovate.json were tested in a development environment per our team instructions.

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