fix(ci): run gen_lockfile.py in container for OpenSSL compat

The RHAI index provides a cryptography package built against
OpenSSL 3.2+, which is unavailable on GitHub Actions runners
(Ubuntu 24.04 ships OpenSSL 3.0.x). This causes nightly schedule
builds to fail at the "Regenerate distribution artifacts" step
with: ImportError: libcrypto.so.3: version `OPENSSL_3.2.0' not found

PR #510 fixed this for the update-lockfiles workflow by using
run_gen_lockfile.sh (which runs inside a UBI9 container with
OpenSSL 3.5), but the regenerate-artifacts action still ran
gen_lockfile.py directly on the runner.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: EleanorWho

.github/actions/regenerate-artifacts/action.yml

@@ -24,5 +24,5 @@ runs:
           export OGX_VERSION="$OGX_VERSION_OVERRIDE"
         fi
         uv run build/gen_config.py
-        uv run build/gen_lockfile.py
+        ./build/run_gen_lockfile.sh
         uv run build/gen_containerfile.py