Update rtd config file

[adam-a-a]

Addresses issue:

Summary/Motivation:

Readthedocs check is failing and other checks won't run until the RTD check passes. Let's fix it.

Changes proposed in this PR:

• update config file following https://github.com/openedx/edx-cookiecutters/issues/416

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[codecov[bot]]

Codecov Report

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

Comparison is base (696dacc) 89.83% compared to head (9c187c1) 89.83%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #220 +/- ## ======================================= Coverage 89.83% 89.83% ======================================= Files 77 77 Lines 9307 9307 ======================================= Hits 8361 8361 Misses 946 946 ```

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