feat: add support for cargo workspaces

[woile]

Description

This PR adds support for Cargo.toml workspaces.

When the root Cargo.toml of a project is:

[workspace.package]
version = "0.1.0"

In your apps you can have a Cargo.toml with:

[package]
version = { workspace = true }

Checklist

• Add test cases to all the changes you introduce
• Run ./scripts/format and ./scripts/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01 🎉

Comparison is base (eb39f8b) 97.31% compared to head (ded9fef) 97.32%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #754      +/-   ##
==========================================
+ Coverage   97.31%   97.32%   +0.01%     
==========================================
  Files          42       42              
  Lines        2045     2054       +9     
==========================================
+ Hits         1990     1999       +9     
  Misses         55       55              

Flag	Coverage Δ
unittests	97.32% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
commitizen/__version__.py	100.00% <100.00%> (ø)
commitizen/providers.py	97.50% <100.00%> (+0.20%)	⬆️

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