Fix dtype promotion in SEVIRI native reader

[pkhalaj]

• Closes Fix the bug with satpy when using numpy 2.x which leads to SEVIRI resampled files having a double size #2981
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.08%. Comparing base (fd2cec6) to head (da84875).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2983      +/-   ##
==========================================
- Coverage   96.10%   96.08%   -0.02%     
==========================================
  Files         377      377              
  Lines       55147    55150       +3     
==========================================
- Hits        52997    52992       -5     
- Misses       2150     2158       +8     

Flag	Coverage Δ
behaviourtests	3.94% <0.00%> (-0.01%)	⬇️
unittests	96.18% <100.00%> (-0.02%)	⬇️

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[coveralls]

Pull Request Test Coverage Report for Build 11929321333

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 8 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.01%) to 96.193%

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Files with Coverage Reduction	New Missed Lines	%
satpy/tests/utils.py	2	93.16%
satpy/tests/reader_tests/gms/test_gms5_vissr_l1b.py	3	98.67%
satpy/tests/reader_tests/gms/test_gms5_vissr_navigation.py	3	97.18%

Totals
Change from base Build 11815057382:	-0.01%
Covered Lines:	53236
Relevant Lines:	55343

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💛 - Coveralls

[pnuu]

Thanks for the simple fix! Just one suggestion in-line. And I changed the topic so that the actual issue is shown. The topics are used in the changelog, so "Fix bug #2981" wouldn't tell much :-)

[pkhalaj]

Thanks for the simple fix! Just one suggestion in-line. And I changed the topic so that the actual issue is shown. The topics are used in the changelog, so "Fix bug #2981" wouldn't tell much :-)

Thanks. I just applied your suggestion regarding type checking the computed values as well.

[mraspaud]

LGTM! thanks for the fix.

[sfinkens]

Nice, thanks!