chore: updated Dutch translations

[Seboeb]

SUMMARY

This PR updates the .po and .json file for the (missing) Dutch translations.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

• Activate nl (Dutch) language in superset_config.py
• Navigate through dashboards and UI of Superset

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[github-actions]

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[mistercrunch]

I don't speak dutch but this looks thoughtful and seems like great progress forward. It'd be great to have some sort of dashboard with per-language completion %

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.47%. Comparing base (76d897e) to head (91b2551).
Report is 1094 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #28710       +/-   ##
===========================================
+ Coverage   60.48%   83.47%   +22.98%     
===========================================
  Files        1931      523     -1408     
  Lines       76236    37575    -38661     
  Branches     8568        0     -8568     
===========================================
- Hits        46114    31366    -14748     
+ Misses      28017     6209    -21808     
+ Partials     2105        0     -2105     

Flag	Coverage Δ
hive	49.01% <ø> (-0.16%)	⬇️
javascript	?
mysql	77.09% <ø> (?)
postgres	77.23% <ø> (?)
presto	53.56% <ø> (-0.25%)	⬇️
python	83.47% <ø> (+19.98%)	⬆️
sqlite	76.68% <ø> (?)
unit	58.94% <ø> (+1.32%)	⬆️

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[mistercrunch]

I just fixed the end-of-file error, for next PR please install the pre-commit hooks -> https://superset.apache.org/docs/contributing/development/#git-hooks

[Seboeb]

I just fixed the end-of-file error, for next PR please install the pre-commit hooks -> https://superset.apache.org/docs/contributing/development/#git-hooks

Thanks, and yes I will do so