Update Lightning
This pull request **introduces 2 alerts** and **fixes 2** when merging 7c84696134f25a2a0db4deeb0956490025789cb0 into b147370de5a05ef29e96901c383a0ac81d9e352e - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-549dc7ace7021ee28a131c1ef4e5f669078256bb)

**new alerts:**

* 2 for Syntax error

**fixed alerts:**

* 1 for Signature mismatch in overriding method
* 1 for Unused import
Fixes:

- row_log_interval -> log_every_n_steps
- log_save_interval -> flush_logs_every_n_steps
- LearningRateLogger -> LearningRateMonitor