[0.7.0] Fix docs and deps

[Tim-Zhang]

• docs: Remove feature protobuf-codec which does not exist anymore
• docs: Fix the warning "unclosed HTML tag Notifier"
• Remove the unused dependency

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (0.7.0@edc11a7). Click here to learn what that means. Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 0.7.0 #213 +/- ## ======================================== Coverage ? 24.38% ======================================== Files ? 16 Lines ? 2526 Branches ? 0 ======================================== Hits ? 616 Misses ? 1910 Partials ? 0 ```

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