Print timestep info in scientific notation (#614)

### Description
This change ensures the timestep info is printed in scientific notation
in the output logfile.

### Related issues
By default, it only prints in scientific notation if the number is
greater than 1e10.

### Checklist
_Before this pull request can be reviewed, all of these tasks should be
completed. Denote completed tasks with an `x` inside the square brackets
`[ ]` in the Markdown source below:_
- [x] I have added a description (see above).
- [ ] I have added a link to any related issues see (see above).
- [x] I have read the [Contributing
Guide](https://github.com/quokka-astro/quokka/blob/development/CONTRIBUTING.md).
- [ ] I have added tests for any new physics that this PR adds to the
code.
- [x] I have tested this PR on my local computer and all tests pass.
- [x] I have manually triggered the GPU tests with the magic comment
`/azp run`.
- [x] I have requested a reviewer for this PR.

src/simulation.hpp

@@ -1269,7 +1269,7 @@ template <typename problem_t> void AMRSimulation<problem_t>::timeStepWithSubcycl
 
 	if (Verbose()) {
 		amrex::Print() << "[Level " << lev << " step " << istep[lev] + 1 << "] ";
-		amrex::Print() << "ADVANCE with time = " << tNew_[lev] << " dt = " << dt_[lev] << '\n';
+		amrex::Print() << "ADVANCE with time = " << std::scientific << tNew_[lev] << " dt = " << std::scientific << dt_[lev] << '\n';
 	}
 
 	// Advance a single level for a single time step, and update flux registers