Fix / snapshot_base params_to_skip_update

[WilliamHPNielsen]

We found out that there's currently a bug in snapshot_base: if the snapshot encounters a parameter that should be skipped (as given by the params_to_skip_update argument), it will skip the update of all subsequent parameters.

Changes proposed in this pull request:

• Add a test for this behaviour
• Fix the skipping logic
• Add Optional to the type annotations for params_to_skip_update

@QCoDeS/core

[codecov]

Codecov Report

Merging #1584 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1584      +/-   ##
==========================================
+ Coverage   72.33%   72.34%   +0.01%     
==========================================
  Files         116      116              
  Lines       12389    12390       +1     
==========================================
+ Hits         8962     8964       +2     
+ Misses       3427     3426       -1

[astafan8]

This looks ok, but perhaps the test can be improved.

[astafan8]

Time for this to get in :)

Thanks for improving the test!