Support Python 3.x for changelog scripts.

[millems]

No description provided.

[codecov-io]

Codecov Report

Merging #1276 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #1276      +/-   ##
============================================
- Coverage      70.2%   70.16%   -0.05%     
  Complexity      188      188              
============================================
  Files           776      776              
  Lines         24129    24129              
  Branches       1799     1799              
============================================
- Hits          16940    16930      -10     
- Misses         6408     6415       +7     
- Partials        781      784       +3

Flag	Coverage Δ	Complexity Δ
#unittests	70.16% <ø> (-0.05%)	188 <ø> (ø)

Impacted Files	Coverage Δ	Complexity Δ
.../http/nio/netty/internal/NettyRequestExecutor.java	64.86% <0%> (-7.03%)	0% <0%> (ø)
...on/awssdk/services/kinesis/KinesisRetryPolicy.java	85.71% <0%> (ø)	0% <0%> (ø)	⬇️
...nio/netty/internal/OldConnectionReaperHandler.java	90.9% <0%> (+9.09%)	0% <0%> (ø)	⬇️

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