chore: explicitly declare license with classifier

[WilliamRoyNelson]

Description

Adds PyPI project classifiers to explicitly declare the software license.
Classifiers are used to add information to the classifiers panel in PyPI. Example from NumPy:

Motivation and Context

The reason that it is very important for this information to be present is that in an enterprise environment, security tools like Sonatype Nexus IQ are used to manage open source software risk. Nexus IQ specifically can be configured to classify packages according to their license. This prevents developers from inadvertently using licenses like GNU General Public License v2.0 without realizing that they may be legally obligated to make their entire project open source.

Because these libraries do not declare their license via classifiers, automated tools cannot properly determine the license and may treat them as high-risk packages.

How Has This Been Tested?

I have made nearly identical changes to other Open Source projects:
Examples:
trubrics/streamlit-feedback#12
bashtage/linearmodels#545
matthewwardrop/formulaic#144

CheckList

• PR title addresses the issue accurately and concisely
• Updates Documentation and Docstrings
• Adds tests
• Adds instrumentation (logs, or UI events)

[boring-cyborg]

Congratulations on your first Pull Request and welcome to Amundsen community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/amundsen-io/amundsen/blob/main/CONTRIBUTING.md)

[kristenarmes]

thanks for the PR @WilliamRoyNelson! can you follow the steps here to rebase the branch to include a sign off on your commit, and then it should be good to merge

[WilliamRoyNelson]

thanks for the PR @WilliamRoyNelson! can you follow the steps here to rebase the branch to include a sign off on your commit, and then it should be good to merge

It looks like the DCO check now passes. I think I did it correctly. I've never used this Git feature before, thank you for pointing it out to me!

[boring-cyborg]

Awesome work, congrats on your first merged pull request!