*: update tidb

[disksing]

Signed-off-by: disksing i@disksing.com

What problem does this PR solve?

update tidb dependency

What is changed and how it works?

• go get -u tidb
• update mockChecksumKVClient to meet new interface
• use kv.PriorityLow instead of tikvstore.PriorityLow

Check List

Tests

• Unit test

Release note

• No release note

[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[disksing]

/run-check_release_note

[kennytm]

/run-check-release-note

/lgtm

[tisonkun]

@disksing iiuc Release Note should be Release note because it checks exactly matched.

[disksing]

@disksing iiuc Release Note should be Release note because it checks exactly matched.

Interesting. Release Note is from the PR template.

[disksing]

/run-check-release-note

[overvenus]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• kennytm
• overvenus

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After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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[overvenus]

/lgtm

[kennytm]

/merge

[ti-chi-bot]

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

Commit hash: f848716