Update example_data submodule with plasma mechanisms

[speth]

Changes proposed in this pull request

• Update example_data submodule. This fixes the current failures to run the examples and build the full documentation.
• Follow-on to Two-Term Boltzmann Equation solver #1887

Checklist

• The pull request includes a clear description of this code change
• Commit messages have short titles and reference relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review