Fix issue related to tests

[alifbe]

• Fix issues with mypy (make sure to have explicit optional type)
• Add PR Temporarily disabling ResInsight tests  #516 from @vkip to temporarily disable ResInsight tests

[ertomatic]

Can one of the admins verify this patch?

[codecov-commenter]

Codecov Report

Merging #517 (b659947) into master (51f5860) will decrease coverage by 1.36%.
The diff coverage is 100.00%.

❗ Current head b659947 differs from pull request most recent head 7c6ac66. Consider uploading reports for the commit 7c6ac66 to get more accurate results

@@            Coverage Diff             @@
##           master     #517      +/-   ##
==========================================
- Coverage   87.55%   86.20%   -1.36%     
==========================================
  Files          49       49              
  Lines        7030     7030              
==========================================
- Hits         6155     6060      -95     
- Misses        875      970      +95     

Impacted Files	Coverage Δ
src/subscript/eclcompress/eclcompress.py	95.53% <ø> (ø)
src/subscript/fmuobs/fmuobs.py	82.18% <ø> (ø)
src/subscript/presentvalue/presentvalue.py	86.31% <ø> (ø)
src/subscript/ri_wellmod/ri_wellmod.py	38.08% <ø> (-24.62%)	⬇️
src/subscript/summaryplot/summaryplot.py	83.88% <ø> (ø)
src/subscript/check_swatinit/plotter.py	94.59% <100.00%> (ø)
src/subscript/csv_merge/csv_merge.py	93.79% <100.00%> (ø)
src/subscript/fmuobs/parsers.py	95.45% <100.00%> (ø)
src/subscript/prtvol2csv/prtvol2csv.py	93.27% <100.00%> (ø)

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[vkip]

LGTM :)