Add a quick test that ensures `ganttDb` correctly adds `1d` (1 day),
even on days with 25 hours.
This test only runs if the test PC has the TZ='America/Los_Angeles'
set (California has daylight savings).
I've added a test to the GitHub Actions `test.yml` action too for this.
It should only add about 5 seconds to each test, so it isn't too bad.
Reverts commits:
- Disabling coveralls temporarilly
aedf066337
- Tmo disabling of coveralls
a6b4cb24b8
I'm not 100% sure whether the `parallel` option is needed,
but I've left it disabled for now, since it'd would mean that we need
to merge both the `test.yml` and the `e2e.yml` file together.
