Codecov yml token addition

[michaelgsharp]

Due to the issue of codecov not being able to find the pipeline for some reason, adding in the codecov yml token so it knows where to upload the code coverage stats to.

Also updating the nuget for the codecov uploader.

[codecov]

Codecov Report

Merging #5950 (3ed9261) into main (d13045f) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #5950      +/-   ##
==========================================
+ Coverage   68.20%   68.26%   +0.05%     
==========================================
  Files        1142     1142              
  Lines      242534   242534              
  Branches    25378    25378              
==========================================
+ Hits       165420   165562     +142     
+ Misses      70416    70289     -127     
+ Partials     6698     6683      -15     

Flag	Coverage Δ
Debug	68.26% <ø> (+0.05%)	⬆️
production	62.94% <ø> (+0.07%)	⬆️
test	88.59% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
....ML.AutoML/PipelineSuggesters/PipelineSuggester.cs	78.74% <0.00%> (-3.15%)	⬇️
src/Microsoft.ML.Transforms/Text/LdaTransform.cs	88.44% <0.00%> (+0.14%)	⬆️
src/Microsoft.ML.Data/Utils/LossFunctions.cs	67.35% <0.00%> (+0.51%)	⬆️
...oft.ML.StandardTrainers/Standard/SdcaMulticlass.cs	92.15% <0.00%> (+1.02%)	⬆️
...crosoft.ML.StandardTrainers/Optimizer/Optimizer.cs	73.12% <0.00%> (+1.15%)	⬆️
src/Microsoft.ML.Sweeper/AsyncSweeper.cs	72.78% <0.00%> (+1.36%)	⬆️
src/Microsoft.ML.Maml/MAML.cs	26.90% <0.00%> (+1.52%)	⬆️
...crosoft.ML.StandardTrainers/Standard/SdcaBinary.cs	88.13% <0.00%> (+3.07%)	⬆️
src/Microsoft.ML.Data/Training/TrainerUtils.cs	69.67% <0.00%> (+3.81%)	⬆️
...osoft.ML.KMeansClustering/KMeansPlusPlusTrainer.cs	90.76% <0.00%> (+7.15%)	⬆️
... and 1 more

[safern]

LGTM