Remove extra backtick

[mauricesvp]

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Why this change is necessary and useful

Fixes extra backtick in README.

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This change is 

[codecov[bot]]

Codecov Report

Merging #4225 (3b607df) into master (c3c0332) will decrease coverage by 0.09%. The diff coverage is n/a.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4225 +/- ## ========================================== - Coverage 89.67% 89.58% -0.09% ========================================== Files 34 34 Lines 4445 4445 ========================================== - Hits 3986 3982 -4 - Misses 459 463 +4 ```

[mergify[bot]]

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