Update TinkerPop to latest 3.6.4

[vkagamlyk]

Summary

Update TinkerPop to latest 3.6.4

Description

The current release uses TinkerPop 3.4.8 as dependency, which is outdated. Bumping grader.properties to 3.6.4 resolved the issue.

Additional Reviewers

@birschick-bq @xiazcy @alexey-temnikov @kylepbit @Cole-Greer

[codecov-commenter]

Codecov Report

Merging #230 (cb300dc) into develop (0cff376) will decrease coverage by 0.18%. The diff coverage is 17.39%.

@@             Coverage Diff             @@
##           develop     #230      +/-   ##
===========================================
- Coverage    67.53%   67.36%   -0.18%     
===========================================
  Files          121      121              
  Lines         5874     5886      +12     
  Branches       585      585              
===========================================
- Hits          3967     3965       -2     
- Misses        1556     1570      +14     
  Partials       351      351              

Impacted Files	Coverage Δ
...gremlindatamodel/SchemaHelperGremlinDataModel.java	0.00% <0.00%> (ø)
...s/neptune/gremlin/GremlinConnectionProperties.java	73.50% <ø> (ø)
...eptune/gremlin/adapter/converter/SqlConverter.java	80.55% <0.00%> (ø)
...r/converter/ast/nodes/select/GremlinSqlSelect.java	91.54% <0.00%> (ø)
...erter/ast/nodes/select/GremlinSqlSelectSingle.java	75.60% <0.00%> (ø)
...gremlin/adapter/results/pagination/Pagination.java	75.00% <ø> (ø)
...s/neptune/jdbc/utilities/ConnectionProperties.java	67.69% <ø> (ø)
...software/aws/neptune/jdbc/utilities/SshTunnel.java	8.62% <ø> (ø)
...ware/aws/neptune/gremlin/GremlinQueryExecutor.java	42.02% <33.33%> (-2.04%)	:arrow_down: