release the transport when version verification failed

[Nicole00]

fix #399

[codecov-commenter]

Codecov Report

Merging #402 (2c14bb9) into master (ac50d72) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master     #402      +/-   ##
============================================
- Coverage     63.98%   63.96%   -0.02%     
  Complexity      709      709              
============================================
  Files            65       65              
  Lines          3343     3344       +1     
  Branches        477      477              
============================================
  Hits           2139     2139              
- Misses          882      883       +1     
  Partials        322      322              

Impacted Files	Coverage Δ
...vesoft/nebula/client/graph/net/SyncConnection.java	50.43% <0.00%> (-0.45%)	⬇️

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