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.

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✨ 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.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: wk989898

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

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [wk989898]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-06-08 03:31:24.741887407 +0000 UTC m=+757985.812204797: ☑️ agreed by wk989898.

[wk989898]

/test next-gen