CI: update actions/labeler to v5

CI: update actions/labeler to v5

* Version 5 of this action updated the runtime to Node.js 20.
 All scripts are now run with Node.js 20 instead of Node.js 16
 and are affected by any breaking changes between Node.js 16 and 20.
* adapt the labeler configuration to the new format

Follow-up to #16251 this was reverted with b870c16534c05ddc94149c6ff56976d8de8a353f
Link: https://github.com/openwrt/openwrt/pull/16451
Signed-off-by: Goetz Goerisch <ggoerisch@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/16451
Signed-off-by: Robert Marko <robimarko@gmail.com>