Update rand requirement from 0.8 to 0.9

[loongs-zhang]

// Describe your PR here; eg. Fixes #issueNo

Make sure that:

• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.27%. Comparing base (7299975) to head (a6fabe9).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #390      +/-   ##
==========================================
- Coverage   77.33%   77.27%   -0.06%     
==========================================
  Files          45       45              
  Lines        5149     5149              
==========================================
- Hits         3982     3979       -3     
- Misses       1167     1170       +3     

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