support json type for mysql downstream

[D3Hunter]

What problem does this PR solve?

as title

What is changed and how it works?

change go-mysql to store json as string and update dependency version

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
• Need to update the dm/dm-ansible
• Need to be included in the release note

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• glorv
• lance6716

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[D3Hunter]

/run-unit-test

[lance6716]

let's wait https://ci.pingcap.net/blue/organizations/jenkins/dm_ghpr_new_test/detail/dm_ghpr_new_test/3274/pipeline

CI passed

[glorv]

Due to the outdated ci scripts, we will force merge this PR.