deps: bump client-go for nextgen shared lock

[cfzjywxk]

What problem does this PR solve?

Issue Number: ref #5206

TiCDC master still depends on an older github.com/tikv/client-go/v2 revision that does not contain the API v2 lock-key re-encoding fix needed by the TiDB shared-lock feature.

Related TiDB issue: pingcap/tidb#66154
Client-go fix PR: tikv/client-go#1987

This PR follows the same dependency strategy as #5203 and consumes the minimal client-go branch for TiCDC:

• https://github.com/tikv/client-go/tree/release-nextgen-202603-ticdc
• github.com/tikv/client-go/v2 v2.0.8-0.20260605035552-78dc334b882b

What is changed and how it works?

• Bump github.com/tikv/client-go/v2 to the minimal 78dc334 pseudo-version.
• Bump github.com/pingcap/kvproto only as required by that client-go version.
• Keep github.com/pingcap/tidb, github.com/tikv/pd/client, google.golang.org/grpc, and golang.org/x/* unchanged.

Check List

Tests

• Unit test
• Manual test

Local checks run:

• go mod tidy
• git diff --check
• NEXT_GEN=1 make cdc
• go test --tags=nextgen ./cmd/cdc
• go test --tags=nextgen ./pkg/txnutil/gc/...
• go test --tags=nextgen ./logservice/logpuller/...
• go test --tags=nextgen ./logservice/txnutil/...
• go test --tags=nextgen -timeout=2m ./pkg/upstream/...

Note: pkg/pdutil/TestGetSourceID times out locally in the same way on clean origin/master, so it is not introduced by this dependency bump.

Questions

Will it cause performance regression or break compatibility?

No expected compatibility impact. The dependency change is limited to client-go and its required kvproto version for shared-lock support.

Do you need to update user documentation, design documentation or monitoring documentation?

No.

Release note

None.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR updates two Go module dependencies to newer commits: github.com/pingcap/kvproto and github.com/tikv/client-go/v2. Both changes are pinned commit updates within go.mod.

Changes

Dependency Updates

Layer / File(s)	Summary
kvproto and client-go dependency version bumps go.mod	github.com/pingcap/kvproto and github.com/tikv/client-go/v2 are each updated to newer commit hashes.

Estimated Code Review Effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 Two modules hop along the path,
kvproto and client dashed,
Commits flow newer, fresh and bright,
Dependencies aligned just right! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically summarizes the main change: bumping the client-go dependency to support nextgen shared lock functionality.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The PR description comprehensively addresses all required template sections with clear problem statement, detailed changes, thorough testing documentation, and explicit answers to compatibility and documentation questions.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[gemini-code-assist]

Code Review

This pull request updates the github.com/pingcap/kvproto and github.com/tikv/client-go/v2 dependencies to newer versions in go.mod and go.sum. I have no feedback to provide.

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[cfzjywxk]

@tenfyzhong @3AceShowHand @wk989898
PTAL it is critical important for correctness on nextgen tidb build.

[wk989898]

/test next-gen

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3AceShowHand, wk989898

The full list of commands accepted by this bot can be found here.

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Details

Needs approval from an approver in each of these files:

• OWNERS [3AceShowHand,wk989898]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-06-08 03:31:24.741887407 +0000 UTC m=+757985.812204797: ☑️ agreed by wk989898.
• 2026-06-09 03:51:47.479686909 +0000 UTC m=+845608.550004309: ☑️ agreed by 3AceShowHand.

[wk989898]

/retest