fix: downgrade react-markdown to v8 that supports React version < v18

[MartinCupela]

🎯 Goal

fix #2455 fix #2234

🛠 Implementation details

Only react-markdown was downgraded while the libraries used to create remark and rehype plugins have not. Custom rehype or remark plugins using visit function from the library unist-util-visit will have to check the index and parent arguments of the Visitor function for null and undefined.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.50%. Comparing base (061d1a3) to head (48e8def). Report is 8 commits behind head on release-v11.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-v11 #2461 +/- ## =============================================== - Coverage 85.51% 85.50% -0.02% =============================================== Files 393 393 Lines 9127 9125 -2 Branches 2492 2357 -135 =============================================== - Hits 7805 7802 -3 - Misses 924 1121 +197 + Partials 398 202 -196 ```

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[stream-ci-bot]

:tada: This PR is included in version 11.23.4 :tada:

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot :package::rocket:

[stream-ci-bot]

:tada: This PR is included in version 12.0.0-rc.8 :tada:

The release is available on:

• GitHub release
• npm package (@rc dist-tag)

Your semantic-release bot :package::rocket: