Bump operator version to 1.3.1 (#4433)

[ti-srebot]

cherry-pick #4433 to release-1.3
You can switch your code base to this Pull Request by using git-extras:

# In tidb-operator repo:
git pr https://github.com/pingcap/tidb-operator/pull/4438

After apply modifications, you can push your change to this PR via:

git push [email protected]:ti-srebot/tidb-operator.git pr/4438:release-1.3-b2a0f19c2ed3

---

What problem does this PR solve?

What is changed and how does it work?

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

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

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• DanielZhangQD

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[ti-srebot]

@KanShiori you're already a collaborator in bot's repo.

[DanielZhangQD]

LGTM

[DanielZhangQD]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 94a170a

[codecov-commenter]

Codecov Report

Merging #4438 (94a170a) into release-1.3 (ce5d391) will increase coverage by 2.71%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           release-1.3    #4438      +/-   ##
===============================================
+ Coverage        62.37%   65.08%   +2.71%     
===============================================
  Files              184      188       +4     
  Lines            19775    22177    +2402     
===============================================
+ Hits             12334    14435    +2101     
- Misses            6296     6503     +207     
- Partials          1145     1239      +94     

Flag	Coverage Δ
e2e	38.25% <ø> (?)
unittest	62.38% <ø> (+0.01%)	⬆️