chore(deps): Bump @backstage/plugin-techdocs-node

Bumps [@backstage/plugin-techdocs-node](https://github.com/backstage/backstage/tree/HEAD/plugins/techdocs-node) from 1.12.11 to 1.12.15.
- [Release notes](https://github.com/backstage/backstage/releases)
- [Changelog](https://github.com/backstage/backstage/blob/master/plugins/techdocs-node/CHANGELOG.md)
- [Commits](https://github.com/backstage/backstage/commits/HEAD/plugins/techdocs-node)

---
updated-dependencies:
- dependency-name: "@backstage/plugin-techdocs-node"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>