chore: add cargo to dependabot

[vil02]

Pull Request Template

Description

Please include a summary of the change and which issue (if any) is fixed.
A brief description of the algorithm and your implementation method can be helpful too. If the implemented method/algorithm is not so
well-known, it would be helpful to add a link to an article explaining it with more details.

Type of change

Please delete options that are not relevant.

This PR adds makes dependabot keep the cargo dependencies up-to-date. Continuation of #690. Similar to TheAlgorithms/Java#5123.

@siriak please have a look.

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.

Please make sure that if there is a test that takes too long to run ( > 300ms), you #[ignore] that or
try to optimize your code or make the test easier to run. We have this rule because we have hundreds of
tests to run; If each one of them took 300ms, we would have to wait for a long time.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.95%. Comparing base (4e59645) to head (45a4b5d).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #728   +/-   ##
=======================================
  Coverage   94.95%   94.95%           
=======================================
  Files         303      303           
  Lines       22533    22533           
=======================================
  Hits        21396    21396           
  Misses       1137     1137           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[siriak]

Looks good, thanks!