feat: add splunk.distro.version resource attribute

[rauno56]

Description

Adds splunk.distro.version resource attribute.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Added automated tests

Checklist:

• Unit tests have been added/updated
• Change file has been generated (npm run change:new)
• Delete this branch (after the PR is merged)

[codecov-commenter]

Codecov Report

Merging #475 (29d6d15) into main (d8a13ba) will increase coverage by 0.24%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #475      +/-   ##
==========================================
+ Coverage   76.33%   76.57%   +0.24%     
==========================================
  Files          21       22       +1     
  Lines         676      683       +7     
  Branches      157      157              
==========================================
+ Hits          516      523       +7     
  Misses        160      160              

Impacted Files	Coverage Δ
src/detectors/DistroDetector.ts	100.00% <100.00%> (ø)
src/resource.ts	88.23% <100.00%> (+0.73%)	⬆️

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