Refactor sieve of Eratosthenes implementation

[TruongNhanNguyen]

Checklist:

• I ran bellow commands using the latest version of rust nightly.
• I ran cargo clippy --all -- -D warnings just before my last commit and fixed any issue that was found.
• I ran cargo fmt just before my last commit.
• I ran cargo test just before my last commit and all tests passed.
• I added my algorithm to the corresponding mod.rs file within its own folder, and in any parent folder(s).
• I added my algorithm to DIRECTORY.md with the correct link.
• I checked COUNTRIBUTING.md and my code follows its guidelines.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.95%. Comparing base (1d9c510) to head (a4ad117).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #724      +/-   ##
==========================================
- Coverage   94.95%   94.95%   -0.01%     
==========================================
  Files         303      303              
  Lines       22533    22531       -2     
==========================================
- Hits        21396    21394       -2     
  Misses       1137     1137              

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