fix: update shutter widget color when closed

[fdrgsp]

In this PR the gray color (instead of magenta) is used to indicate when the shutter is closed, making it easier to distinguish its state.

NOTE: to fix pre-commit I had to update the types of the MDAWidget execute_mda and run_mda methods.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.65%. Comparing base (68f8dee) to head (d0d2d99).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #399   +/-   ##
=======================================
  Coverage   90.65%   90.65%           
=======================================
  Files          85       85           
  Lines        9360     9362    +2     
=======================================
+ Hits         8485     8487    +2     
  Misses        875      875           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.