Remove TracisCI config file

[astrogeco]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I reviewed the cFS README.md file to see if the feature is in the major future work.
• I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
The file is no longer maintained but its presence in the repository still triggers TravisCI runs. As we continue to upgrade our CI pipelines this outdated file might result in misleading results.

Describe the solution you'd like
Remove the .travis.yml file

Describe alternatives you've considered
None

Additional context
All of the Travis CI functionality has been migrated to Github Actions. Config files are stored in .github/workflows.

Requester Info
Gerardo E. Cruz-Ortiz | NASA