Glean-parser

- Warn about empty or TODO-tagged data reviews in the list ([634](https://github.com/mozilla/glean_parser/pull/634))
- Allow `unit` field on all metrics, but warn for all but quantity and custom distribution ([636](https://github.com/mozilla/glean_parser/pull/636))

- Allow `unit` field for string again, but warn about it in the linter ([634](https://github.com/mozilla/glean_parser/pull/634))

- Allow `unit` field for custom distribution again ([633](https://github.com/mozilla/glean_parser/pull/633))

- Add Ruby log outputter (`ruby_server`) ([620](https://github.com/mozilla/glean_parser/pull/620))
- BREAKING CHANE: `ping` lifetime metrics on the events ping are now disallowed ([625](https://github.com/mozilla/glean_parser/pull/625))
- Disallow `unit` field for anything but quantity ([630](https://github.com/mozilla/glean_parser/pull/630)).
Note that this was already considered the case, now the code enforces it.

- BREAKING CHANGE: Dropped support for Python 3.6 ([615](https://github.com/mozilla/glean_parser/issues/615))
- Allow metadata to configure precise timestamps in pings ([592](https://github.com/mozilla/glean_parser/pull/592))

- Small updates to the `javascript_server` tempalte to address lint warnings ([598](https://github.com/mozilla/glean_parser/pull/598))