Fix: Data race in topic message query

[bamzedev]

Description:
This PR fixes data race in TopicMessageQuery.

Related issue(s):

Fixes #786

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[codecov]

Codecov Report

Patch coverage: 67.94% and project coverage change: +0.09% 🎉

Comparison is base (3f01d98) 61.67% compared to head (a2a2bcd) 61.77%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #787      +/-   ##
===========================================
+ Coverage    61.67%   61.77%   +0.09%     
===========================================
  Files          164      164              
  Lines        33602    33679      +77     
===========================================
+ Hits         20723    20804      +81     
+ Misses       11587    11581       -6     
- Partials      1292     1294       +2     

Files Changed	Coverage Δ
contract_id.go	69.61% <62.85%> (-1.62%)	⬇️
account_id.go	65.86% <65.71%> (+0.76%)	⬆️
topic_message_query.go	91.42% <100.00%> (+0.35%)	⬆️

... and 5 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication