Exclude LAS files from GitHubs Language Stats

[dcslagel]

Description:

This commit updates how GitHub displays Lasio's language breakout by
excluding the *.las files which get mis-identified as Lasso files.
See: https://github.com/github/linguist#detectable

Tests:

These are results from running gitHub-linguist on local development machine:
see:
https://github.com/github/linguist#installation

Before this branch:

91.13%  Lasso
4.69%   Jupyter Notebook
4.18%   Python
0.01%   Dockerfile

After this branch:

52.81%  Jupyter Notebook
47.13%  Python
0.06%   Dockerfile

Let me know if this change could be accepted (or rejected) or
needs some additional changes to be approved and merged.

Thank you,
DC

[kinverarity1]

Thanks!