Fix typo in source type

[fuzzybinary]

What does this PR do?

The log attribute for source type had a . instead of an _ which breaks the cross platform contract.

Additional Notes

Anything else we should know when reviewing?

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #1904 (0ee7d13) into develop (0e3a8b0) will decrease coverage by 0.23%.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1904      +/-   ##
===========================================
- Coverage    83.44%   83.21%   -0.23%     
===========================================
  Files          477      477              
  Lines        16911    16877      -34     
  Branches      2512     2507       -5     
===========================================
- Hits         14110    14043      -67     
- Misses        2113     2134      +21     
- Partials       688      700      +12     

Files	Coverage Δ
...in/kotlin/com/datadog/android/log/LogAttributes.kt	0.00% <ø> (ø)

... and 29 files with indirect coverage changes