[SCB-2493] Bump rxjava from 1.1.6 to 1.3.8

[hezhangjian]

No description provided.

[codecov-commenter]

Codecov Report

Merging #2856 (7182cfd) into master (d9e66e1) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #2856      +/-   ##
============================================
- Coverage     77.32%   77.32%   -0.01%     
  Complexity     1419     1419              
============================================
  Files          1615     1615              
  Lines         43334    43334              
  Branches       3672     3672              
============================================
- Hits          33507    33506       -1     
- Misses         8289     8290       +1     
  Partials       1538     1538              

Impacted Files	Coverage Δ
...apache/servicecomb/bizkeeper/BizkeeperCommand.java	95.65% <100.00%> (ø)
...ervicecomb/bizkeeper/BizkeeperHandlerDelegate.java	72.22% <100.00%> (ø)
...b/core/invocation/timeout/PassingTimeStrategy.java	94.44% <0.00%> (-5.56%)	⬇️
.../servicecomb/registry/discovery/DiscoveryTree.java	96.49% <0.00%> (-3.51%)	⬇️
...he/servicecomb/foundation/common/net/NetUtils.java	64.56% <0.00%> (+1.57%)	⬆️

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[hezhangjian]

@liubao68 @fu-turer @tyluffy PTAL