chore(toolkit-lib): include @aws-cdk/cli-plugin-contract in local packaging

[mrgrain]

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.18%. Comparing base (d430b2e) to head (57d291f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #457   +/-   ##
=======================================
  Coverage   79.18%   79.18%           
=======================================
  Files          54       54           
  Lines        6912     6912           
  Branches      773      773           
=======================================
  Hits         5473     5473           
  Misses       1421     1421           
  Partials       18       18           

Flag	Coverage Δ
suite.unit	79.18% <ø> (ø)

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

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.