Fix Cidr type in AWS::EC2::IPAMPool

[kddejong]

Issue #, if available:
fix #4100

Description of changes:

• Fix Cidr type in AWS::EC2::IPAMPool

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.20%. Comparing base (9660076) to head (0456f08).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4101      +/-   ##
==========================================
- Coverage   94.21%   94.20%   -0.01%     
==========================================
  Files         390      390              
  Lines       13407    13407              
  Branches     2653     2653              
==========================================
- Hits        12631    12630       -1     
  Misses        423      423              
- Partials      353      354       +1     

Flag	Coverage Δ
unittests	94.18% <ø> (-0.01%)	⬇️

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