Bio megatron download fix
This pull request **fixes 9 alerts** when merging 4f9ad400d51c3fe596d79169394c70ad936cb80b into d01b7bbc3fdb1bbf14789f71b8f368cf0aa8f86b - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-80363198ef854198c67fd4639ab1230057dd89b0)

**fixed alerts:**

* 9 for Unused import This pull request **fixes 9 alerts** when merging 4bcae26d43c55ea4ee017c78054b68f554e13264 into 9da1d27ddd7f1d5d9b6cd75f7308787976680dd8 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-baeae19bf39b2e47e8b566507936e07fac2cc74d)

**fixed alerts:**

* 9 for Unused import This pull request **fixes 9 alerts** when merging 3965be07e3101dea7d42ff0b27a6e9569ce54fe7 into 1c24a5d35a9680b7436f505a8e69dc8f8373f3c2 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-7a19d7bc10ec9b44f6aa44d402b8649440267c3c)

**fixed alerts:**

* 9 for Unused import
1. Branch for Bio-related notebooks changed to `main`, for the rest of the  notebooks to `v1.0.0b3`
2. Fixed Bio-megatron download issue