Provide a way to release license from persistent interface

[michaelbynum]

Summary/Motivation:

This PR adds a method to the Appsi Gurobi interface to delete the Gurobi model and release the license.

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov[bot]]

Codecov Report

Merging #2480 (a2ec6f2) into main (a2ec6f2) will not change coverage. The diff coverage is n/a.

:exclamation: Current head a2ec6f2 differs from pull request most recent head 02f9cf5. Consider uploading reports for the commit 02f9cf5 to get more accurate results

@@           Coverage Diff           @@
##             main    #2480   +/-   ##
=======================================
  Coverage   86.25%   86.25%           
=======================================
  Files         711      711           
  Lines       78441    78441           
=======================================
  Hits        67657    67657           
  Misses      10784    10784           

Flag	Coverage Δ
linux	83.11% <0.00%> (ø)
osx	73.43% <0.00%> (ø)
other	83.30% <0.00%> (ø)
win	80.20% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[jsiirola]

The Jenkins failure is unrelated (intermittent timing). This is good to go.