Bump 3rdparty/Megatron-LM from 99f23d2 to 2da43ef (NVIDIA#558)

Bumps [3rdparty/Megatron-LM](https://github.com/NVIDIA/Megatron-LM) from
`99f23d2` to `2da43ef`.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/2da43ef4c1b9e76f03b7567360cf7390e877f1b6"><code>2da43ef</code></a>
Merge branch 'mmodal_eval_in_folder' into 'main'</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/e51a3ac1dcd366f51bcb0339ecca31790c3cfcd1"><code>e51a3ac</code></a>
ADLR/megatron-lm!2491 - Move mmodal evaluation code to its own
folder</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/d3c585e90ebd5937243c8d4c9d5d5cf9d61665d6"><code>d3c585e</code></a>
Merge branch 'jbarker/pp_unfreeze' into 'main'</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/1468ab01c079d5e14888dda97d1c99d2cb62afb2"><code>1468ab0</code></a>
ADLR/megatron-lm!2285 - Support --freeze-LM and --freeze-ViT with ranks
that ...</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/cf25d44037af4e9d5ea723918823de9b2416a30c"><code>cf25d44</code></a>
Merge branch 'boxin/nvlm_ckpt_release' into 'main'</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/1da9dad62b97917caacb1fd271abaed403581caa"><code>1da9dad</code></a>
ADLR/megatron-lm!2494 - Add model checkpoint links</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/25b1f33035ad55eeae6b9a4367f987f1fac804dd"><code>25b1f33</code></a>
Merge branch 'helenn-rope-fusion-mem-layout' into 'main'</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/7bb53792831d80007789ff5c60bc1798cbd34548"><code>7bb5379</code></a>
ADLR/megatron-lm!2469 - Correct strides for bshd layout and revert RoPE
tests...</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/b8420a1909980aa3b6750f75b2d7ab8b23338948"><code>b8420a1</code></a>
Merge branch 'group_topk' into 'main'</li>
<li><a
href="https://github.com/NVIDIA/Megatron-LM/commit/d0df563d8739e4dfe2b0e90ba190ac389f165157"><code>d0df563</code></a>
ADLR/megatron-lm!1934 - Support Device-Limited Routing and Sequence
Auxiliary...</li>
<li>Additional commits viewable in <a
href="https://github.com/NVIDIA/Megatron-LM/compare/99f23d2f111d12b73b1fbf386c60517101ff8abe...2da43ef4c1b9e76f03b7567360cf7390e877f1b6">compare
view</a></li>
</ul>
</details>
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