Integrating rmbrualla's pycolmap into gsplat

[ichsan2895]

Compatibilty with pycolmap >=3.13

As requirement.txt, the pycolmap version that compatible with simple_trainer.py is git+https://github.com/rmbrualla/pycolmap@cc7ea4b7301720ac29287dbe450952511b32125e

When I use latest stable pycolmap (3.13.0), it gives error:

$ CUDA_VISIBLE_DEVICES=0 python3 gsplat-dev/examples/simple_trainer.py mcmc --help
Traceback (most recent call last):
  File "/GSPLAT_152n3/gsplat-dev/examples/simple_trainer.py", line 18, in <module>
    from datasets.colmap import Dataset, Parser
  File "/GSPLAT_152n3/gsplat-dev/examples/datasets/colmap.py", line 10, in <module>
    from pycolmap import SceneManager
ImportError: cannot import name 'SceneManager' from 'pycolmap' (/usr/local/lib/python3.10/dist-packages/pycolmap/__init__.py)

Now this PR makes the bug fixes.

[ichsan2895]

Strange, I have run black formatting, but it still fails.

Hmm the sentence, "adding pycolmap >=3.13" might be confusing. How about changing the title "Integrating rmbrualla's pycolmap into gsplat"

gsplat simple_traineer.py needs special pycolmap called rmbrualla pycolmap. If I install rmbrualla's pycolmap, it uninstall the existing pycolmap (if user has it).

So, the PR makes sure it wont break each others (rmbrualla's pycolmap does not need to be installed) since it integrated with gsplat