ci: track engine-test-data semver tags via Renovate

[khvn26]

Problem

The git-submodules manager defaults to versioning: "git", which treats the .gitmodules branch = v3.x.y value as an opaque git ref. Renovate only refreshes that tag's (immutable) commit SHA and never proposes a newer tag, so the engine-test-data submodule has only ever been bumped manually — it stayed on v3.7.0 even after v3.10.0 was released.

Fix

Set versioning: "semver-coerced" on the git-submodules manager so Renovate ranks the semver tags and opens bump PRs (e.g. v3.7.0 → v3.10.0).

Notes

.gitmodules already uses the branch field, so no change is needed there. This is a config-only change; the actual version bump will come as a follow-up Renovate PR.

[github-actions]

File	Coverage		Missing
All files	100%	✅

Minimum allowed coverage is 100%

Generated by 🐒 cobertura-action against e2e2b7b

[codspeed-hq]

Merging this PR will not alter performance

✅ 1 untouched benchmark

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_{Comparing ci/renovate-engine-test-data-semver (e2e2b7b) with main (7e2cfc7)}