fix: update version includes a spurious newline

[rix0rrr]

Our upgrade message has looked like this for a long time:

*****************************************************
*** Newer version of CDK is available [2.1120.0
] ***
*** Upgrade recommended (npm install -g aws-cdk)  ***
*****************************************************

Time to fix it and get rid of that spurious newline.

---

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 88.10%. Comparing base (acefbf8) to head (b4f002e).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1477   +/-   ##
=======================================
  Coverage   88.10%   88.10%           
=======================================
  Files          74       74           
  Lines       10669    10669           
  Branches     1457     1457           
=======================================
  Hits         9400     9400           
  Misses       1241     1241           
  Partials       28       28           

Flag	Coverage Δ
suite.unit	88.10% <100.00%> (ø)

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