chore: fix failing upgrade-aws-cdk-lib workflow

[mrgrain]

In #1002 we introduced a new workflow to just update aws-cdk-lib and nothing else. Turns out upgrading dependency in subprojects wasn't really support in projen and that needed a fix first.

This PR fixes the workflow by importing the updated projen dependencies. The workflow file is renamed to match projen's naming conventions.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.72%. Comparing base (2c0570a) to head (28b6c2c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1016   +/-   ##
=======================================
  Coverage   87.71%   87.72%           
=======================================
  Files          72       72           
  Lines       10077    10077           
  Branches     1327     1327           
=======================================
+ Hits         8839     8840    +1     
+ Misses       1213     1212    -1     
  Partials       25       25           

Flag	Coverage Δ
suite.unit	87.72% <ø> (+<0.01%)	⬆️

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