chore: bump off-dart to 3.18

[g123k]

No description provided.

[g123k]

@monsieurtanuki Is-it OK to fix nulls like this?
I don't really know how the Prices API works

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 6.53%. Comparing base (4d9c7fc) to head (bf32c5f).
Report is 539 commits behind head on develop.

Files with missing lines	Patch %	Lines
...ages/smooth_app/lib/database/dao_osm_location.dart	0.00%	2 Missing ⚠️
...kages/smooth_app/lib/pages/prices/price_model.dart	0.00%	2 Missing ⚠️
...s/smooth_app/lib/pages/locations/osm_location.dart	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5969      +/-   ##
==========================================
- Coverage     9.54%   6.53%   -3.02%     
==========================================
  Files          325     440     +115     
  Lines        16411   24836    +8425     
==========================================
+ Hits          1567    1623      +56     
- Misses       14844   23213    +8369     

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[monsieurtanuki]

@monsieurtanuki Is-it OK to fix nulls like this? I don't really know how the Prices API works

Not it's not. Let me do it.