chore(docs): install rust for .readthedocs.yml

[erikayasuda]

Our readthedocs build is failing currently due to not having Rust installed. This change should fix this, so our docs can be updated.

Currently, the readthedocs builds haven't happened in 2 months (2.8.1). We need at least 2.9.2 to be published.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: erikayasuda/fix-readthedocs
Commit report: a26c471
Test service: dd-trace-py

✅ 0 Failed, 135218 Passed, 41681 Skipped, 7h 15m 14.11s Total duration (2h 35m 36.16s time saved)
⌛ 1 Performance Regression

⌛ Performance Regressions vs Default Branch (1)

• test_span_attribute_schema_service_name[mysvc-v1] - test_asgi.py 11.64s (+10.37s, +815%) - Details

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.52%. Comparing base (c7e92f6) to head (a26c471).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #9817       +/-   ##
===========================================
- Coverage   74.30%   10.52%   -63.79%     
===========================================
  Files        1398     1365       -33     
  Lines      129873   127661     -2212     
===========================================
- Hits        96500    13430    -83070     
- Misses      33373   114231    +80858     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-07-12 21:32:46

Comparing candidate commit a26c471 in PR branch erikayasuda/fix-readthedocs with baseline commit c7e92f6 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 214 metrics, 2 unstable metrics.