upgrade spring boot version to fix the search user failed issue

[nobodyiam]

What's the purpose of this PR

upgrade spring boot version to fix the search user failed issue

Which issue(s) this PR fixes:

Fixes #4360

Brief changelog

• upgrade spring boot version to 2.6.8
• upgrade spring cloud version to 2021.0.2

Follow this checklist to help us incorporate your contribution quickly and easily:

• Read the Contributing Guide before making this pull request.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit tests to verify the code.
• Run mvn clean test to make sure this pull request doesn't break anything.
• Update the CHANGES log.

[codecov-commenter]

Codecov Report

Merging #4366 (c77ca99) into master (9a11168) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4366      +/-   ##
============================================
- Coverage     53.22%   53.21%   -0.01%     
+ Complexity     2675     2674       -1     
============================================
  Files           489      489              
  Lines         15267    15267              
  Branches       1576     1576              
============================================
- Hits           8126     8125       -1     
  Misses         6587     6587              
- Partials        554      555       +1     

Impacted Files	Coverage Δ
...ervice/service/ReleaseMessageServiceWithCache.java	85.88% <0.00%> (-1.18%)	⬇️

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