Missing char in instructions for pip installing pytorch3d.git

[yoDon]

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🐛 Bugs / Unexpected behaviors

The top level tutorials page currently tells visitors to

!pip install torch torchvision
!pip install 'git+https://github.com/facebookresearch/pytorch3d.git

The second line is missing a closing single quote, resulting in errors when visitors try to follow the instructions.

PR submitted as #27

Instructions To Reproduce the Issue:

Please include the following (depending on what the issue is):

1. Any changes you made (git diff) or code you wrote

<put diff or code here>

2. The exact command(s) you ran:
3. What you observed (including the full logs):

<put logs here>

Please also simplify the steps as much as possible so they do not require additional resources to
run, such as a private dataset.