chore: bump CI LuaRocks pin to 3.13.0

[devin-ai-integration]

Requirements

• I have added test coverage for new or changed functionality (CI-only change; existing test suite covers it)
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions (validated locally on Lua 5.3; CI runs 5.1/5.2/5.3/luajit-2.1)

Related issues

None — routine dependency audit of this repo and its examples.

Describe the solution you've provided

Bumps the exact LuaRocks pin used by CI and the install-lua-sdk workflow from 3.12.0 to 3.13.0 (latest LuaRocks release, published 2026-01-28). No shipped code or documented minimums change.

Audit result for the LaunchDarkly dependencies — no change needed:

Dependency	Configured	Latest
C++ Server-side SDK (.github/variables/cpp-sdk-versions.env, example Dockerfiles)	3.13.1	3.13.1
C++ Server-side SDK Redis Source	2.4.1	2.4.1

README "Minimum Version" entries (3.9.0 / 2.1.19) are deliberately left alone — the newer SDK works but is not required.

No deprecated LaunchDarkly C-binding APIs are used by launchdarkly-server-sdk.c / launchdarkly-server-sdk-redis.c; both compile warning-free against C++ server SDK 3.13.1.

Describe alternatives you've considered

Leaving the pin at 3.12.0 (it works); bumping the hello-nginx OpenResty base image (1.21.4.1-0-jammy, quite old) — left out as it is unrelated to this audit and higher risk.

Additional context

Validated locally on Ubuntu 22.04 / Lua 5.3, prebuilt C++ server SDK + Redis Source 2.4.1 dynamic Linux artifacts, Boost 1.81.0:

• luarocks 3.13.0 built both rockspecs (launchdarkly-server-sdk, launchdarkly-server-sdk-redis) successfully.
• luarocks test launchdarkly-server-sdk-2.2.0-0.rockspec → Ran 20 tests ... 20 successes, 0 failures (same result with 3.12-era luarocks and with 3.13.0).
• Ran the hello-lua-server example against a real environment SDK key: it initialized, connected, and printed The sample-feature feature flag evaluates to false. (flag absent in that project, so the default was returned).

Link to Devin session: https://app.devin.ai/sessions/f15a4832f3d24aefaadc15789ad9d241

[devin-ai-integration]

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[devin-ai-integration]

@cursor review