fix: Cleanup zipkin build error

[cijothomas]

#2790 for Zipkin

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 80.7%. Comparing base (702c61d) to head (e1f2d45).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-zipkin/src/exporter/mod.rs	0.0%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2839   +/-   ##
=====================================
  Coverage   80.7%   80.7%           
=====================================
  Files        124     124           
  Lines      23493   23490    -3     
=====================================
  Hits       18961   18961           
+ Misses      4532    4529    -3     

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[gruebel]

👍

[scottgerring]

LGTM.
We should probably reflect on codecov's config, as we find ourselves ignoring it pretty regularly.