Fix some exposure things

[hugobuddel]

Fixes #438

• Remove !OBS.dit and !OBS.ndit if exptime is given as argument to readout().
• Properly reset the detector; undoing any Quantization.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 75.43%. Comparing base (5a47b13) to head (44d880a). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #440 +/- ## ========================================== + Coverage 75.41% 75.43% +0.01% ========================================== Files 64 64 Lines 7830 7835 +5 ========================================== + Hits 5905 5910 +5 Misses 1925 1925 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[hugobuddel]

Almost.. https://github.com/AstarVienna/ScopeSim_Data/actions/runs/9968517615/job/27543935859 I should have ran at least the IRDB tests..

FAILED OSIRIS/tests/test_compiles.py::TestOsirisLongSlitCompiles::test_run_lss_simulation - ValueError: !OBS.dit was not found in rc.__currsys__
FAILED OSIRIS/tests/test_compiles.py::TestOsirisMaatCompiles::test_run_maat_simulation - ValueError: !OBS.dit was not found in rc.__currsys__

I'll fix those