Bump versions of gradle plugins

[pavolloffay]

This removes the warning message:

 Task :jaeger-core:shadowJar 
The SimpleWorkResult type has been deprecated and is scheduled to be removed in Gradle 5.0. Please use WorkResults.didWork() instead.

I wanted to bump only shadow version, but decided to update all in the main gradle script. There is no major version bump.

Signed-off-by: Pavol Loffay [email protected]

[codecov]

Codecov Report

Merging #418 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #418   +/-   ##
=========================================
  Coverage     82.09%   82.09%           
  Complexity      490      490           
=========================================
  Files            66       66           
  Lines          2044     2044           
  Branches        247      247           
=========================================
  Hits           1678     1678           
  Misses          284      284           
  Partials         82       82

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