Bump version to v1.15.0

[Yujie-Xie]

What problem does this PR solve?

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[ti-chi-bot]

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 55.81%. Comparing base (21e4114) to head (7e619cb).

❗ Current head 7e619cb differs from pull request most recent head 0358890. Consider uploading reports for the commit 0358890 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2393      +/-   ##
==========================================
- Coverage   55.85%   55.81%   -0.04%     
==========================================
  Files         329      329              
  Lines       35222    35222              
==========================================
- Hits        19670    19657      -13     
- Misses      13190    13200      +10     
- Partials     2362     2365       +3     

Flag	Coverage Δ
tiup	33.59% <ø> (-0.19%)	⬇️
unittest	22.16% <ø> (ø)

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