v1.4.0-prerelease6

Commits

• [6b341c6]: google (AOSP) lint (Felix Haller)
• [f4b1b4f]: PP-893: keep a history of latest seven day averages (Felix Haller)
• [172c2ce]: PP-893: add postgres test container setup (Felix Haller)
• [d51d6c8]: PP-839: Add unit test. Add Cleanup. (alig)