Update drupal/sparkpost from 2.0.0 to 2.1.0

[violinist-bot]

If you have a high test coverage index, and your tests for this pull request are passing, it should be both safe and recommended to merge this update.

Here is a list of changes between the version you use, and the version this pull request updates to:

• c02696d Issue #3148906 by Project Update Bot, jcnventura, eiriksm: Automated Drupal 9 compatibility fixes
• 5a91210 Issue #3164033 by harishh, volkswagenchick, jcnventura, eiriksm: License "GPL-2.0+" is a deprecated SPDX license identifier, use "GPL-2.0-or-later" instead
• 3e0f009 Issue #3126258 by eiriksm: Add a drupalci.yml file
• 4570670 Issue #3124646 by mo_farhaz, eiriksm: t() calls should be avoided in classes
• 337b185 Issue #3113337 by eiriksm: Drupal 9 readiness

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[eiriksm]

This will now be closed, since it has been superseded by #63.