chore(docs): moved docs/snippets checks to separate step

[dreamorosi]

Description of your changes

As described in #1275, now that we have linting for the code examples for the documentation present in docs/snippets, we want to have a dedicated line in the PR checks so that it's easier to identify failures during a PR authoring/review.

This PR updates the workflow that runs linting & tests by adding a separate and dedicated step for the linting of docs/snippets.

How to verify this change

Related issues, RFCs

Issue number: #1275

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published
• The PR title follows the conventional commit semantics

Breaking change checklist

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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