Broken badge on README

[BenMorel]

Since #53, the CI badge on the README is broken: https://github.com/brick/date-time/workflows/CI/badge.svg

This is because we don't have a single CI workflow anymore, but 3 workflows:

• Coding Style
• Static Analysis
• Tests

Each having its own badge:

• https://github.com/brick/date-time/workflows/Coding%20Style/badge.svg
• https://github.com/brick/date-time/workflows/Static%20Analysis/badge.svg
• https://github.com/brick/date-time/workflows/Tests/badge.svg

@tigitz Do you know of a way to get a single badge for all 3 workflows?

[tigitz]

AFAIU, there doesn't seem to be a way to aggregate those statuses into a single badge, no.

Unless we put all the jobs into a single "CI" workflow and generate a badge from this.

[BenMorel]

I changed the badge to point to the Tests workflow only some time ago in 1879aba. This is good enough for now, we'll revisit this later if needed.

Closing to avoid polluting issues for too long.