Update NoSQLBench version to leverage the latest 5.21.1

[msmygit]

• Updates minor documentation items.
• Leverages NoSQLBench to the latest 5.21.x version.
• Adds dependabot that will help keep the GHA runner versions up to date so as to avoid warnings like as below,

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v2, test-summary/action@v1. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

[grighetto]

Without the VERIFY step, this test is pretty much useless because this is what actually compares the stored data against the pseudo-random generated data.
I don't have the context why the NB update is happening in this PR (if it's for some new feature or compatibility with newer C* versions), but if we could still run the old NB with the verify step in addition to this until it's support in the latest NB version, I think it would be ideal.

[msmygit]

Understood. NB 5.21 doesnt support verify feature yet.

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