Updating the changelog in preparation for the upcoming release

[blnicho]

Summary/Motivation:

Updates the PyUtilib CHANGELOG.txt.

TODO: Fill in the correct version number

Changes proposed in this PR:

• Update the CHANGELOG

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[coveralls]

Coverage remained the same at 63.972% when pulling 81d9946 on update-changelog into cbc58d6 on master.

[coveralls]

Coverage remained the same at 63.972% when pulling 2dbf2f4 on update-changelog into cbc58d6 on master.

[codecov-io]

Codecov Report

Merging #48 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #48   +/-   ##
======================================
  Coverage    64.9%   64.9%           
======================================
  Files          87      87           
  Lines        8685    8685           
======================================
  Hits         5637    5637           
  Misses       3048    3048

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