fix: multiple Queue instances being created

[Shahroz16]

While testing, we noticed there are multiple instances of Queue being created even in Native SDK even though it's using getSingletonInstanceCreate method. On further logging, it was observed, that it might be due to multithreading so we making this method synchronized would fix it.

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[github-actions[bot]]

Pull request title looks good 👍!

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[codecov[bot]]

Codecov Report

Merging #190 (dc01993) into main (4ad1f35) will decrease coverage by 0.51%. The diff coverage is 30.55%.

@@             Coverage Diff              @@
##               main     #190      +/-   ##
============================================
- Coverage     63.28%   62.77%   -0.51%     
  Complexity      218      218              
============================================
  Files            91       91              
  Lines          2059     2090      +31     
  Branches        263      270       +7     
============================================
+ Hits           1303     1312       +9     
- Misses          654      675      +21     
- Partials        102      103       +1     

Impacted Files	Coverage Δ
...essagingpush/CustomerIOFirebaseMessagingService.kt	0.00% <0.00%> (ø)
...stomer/sdk/CustomerIOActivityLifecycleCallbacks.kt	7.40% <0.00%> (-4.36%)	:arrow_down:
sdk/src/main/java/io/customer/sdk/di/DiGraph.kt	100.00% <ø> (ø)
sdk/src/main/java/io/customer/sdk/CustomerIO.kt	74.33% <81.81%> (+0.17%)	:arrow_up:
sdk/src/main/java/io/customer/sdk/queue/Queue.kt	82.07% <100.00%> (+0.34%)	:arrow_up:

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[github-actions[bot]]

Build available to test Version: shahroz-synchronize-override-SNAPSHOT Repository: https://s01.oss.sonatype.org/content/repositories/snapshots/

[mrehan27]

I think we should release this fix soon 👀