Fix datetime conversion bug

[meggart]

This fixes a bug similar to the one described by @felixcremer in rafaqz/Rasters.jl#1000 by rounding to the closest millisecond before converting time stamps to DateTime.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.87%. Comparing base (8bd94a0) to head (afd160e).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #560      +/-   ##
==========================================
+ Coverage   69.80%   69.87%   +0.07%     
==========================================
  Files          14       14              
  Lines        2113     2118       +5     
==========================================
+ Hits         1475     1480       +5     
  Misses        638      638              

Files with missing lines	Coverage Δ
src/DatasetAPI/Datasets.jl	85.54% <100.00%> (+0.12%)	⬆️

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[felixcremer]

This is breaking because it changes the output type to a DateTime. This function should only be called when the prefer_datetime keyword is true.
This is also the cause of the doc build failure.

Suggested change

	round_datetime.(dec)
	prefer_datetime && round_datetime.(dec)

[lazarusA]

unfortunately,

failed to run `@example` block in docs/src/UserGuide/select.md:45-49
│ ```@example subset
│ using CFTime
│ time1 = DateTime360Day(2001,01,16)
│ tos[time = At(time1)]
│ ```
│   exception =
│    promotion of types CFTime.DateTime360Day{CFTime.Period{Int64, Val{1}(), Val{-3}()}, Val{(1900, 1, 1)}()} and DateTime failed to change any arguments
│    Stacktrace:
│      [1] error(::String, ::String, ::String)

[felixcremer]

Is this with my suggestions?

[lazarusA]

Ahh, sorry is still a suggestion! Not merged yet. Sorry, my bad 😞. We need to apply the suggestion to see the effect then.

[lazarusA]

any ideas on why this case is not covered?

failed to run `@example` block in docs/src/UserGuide/select.md:45-49
│ ```@example subset
│ using CFTime
│ time1 = DateTime360Day(2001,01,16)
│ tos[time = At(time1)]
│ ```
│   exception =
│    promotion of types CFTime.DateTime360Day{CFTime.Period{Int64, Val{1}(), Val{-3}()}, Val{(1900, 1, 1)}()} and DateTime failed to change any arguments
│    Stacktrace:
│      [1] error(::String, ::String, ::String)

[lazarusA]

close in #561