- in linux jobs we serialise `tests-ui`, `tests-nim` and appImage
`package` into a single workflow.
- in macos job we serialise `iOS`, `MacOS` builds into a single
workflow.
- we use system `nim` for all jobs and dont have to build nim from
nimbus build system each time.
- installed `nim 2.2.10` on `windows` and `macos` hosts.
- upgraded nim in Docker images and bumped the harbour tags for
`linux` and `android`.
This will help us avoid checkout and `deps` stage for these jobs and we
can free up slots for other jobs.
This way we can do more work in parallel.
Because of this we save:
- `12` minutes of build time in `linux` job.
- `10` minutes of build time in `macos` job.
- `21` minutes of `nim` compile time in `windows` job.