chore: fix cargo deny check by updating unicode allowed list

[cijothomas]

Adding more to https://github.com/open-telemetry/opentelemetry-rust/pull/2936/files

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.4%. Comparing base (f771404) to head (b52685b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2964     +/-   ##
=======================================
- Coverage   81.5%   81.4%   -0.1%     
=======================================
  Files        126     126             
  Lines      24305   24305             
=======================================
- Hits       19809   19804      -5     
- Misses      4496    4501      +5     

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[utpilla]

@cijothomas Could update the nightly version for external-types CI check as well in this PR?