Fixing pandas deprecation

[sotorrio1]

Fixes/Addresses:

Addresses issue #1212

Summary/Motivation:

Currently there is a future warning for a pandas deprecation affecting UQ, SDoE and ODoE when using the file results.py

Changes proposed in this PR:

• cast data type for certain results df columns before assigning a value

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[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 38.77%. Comparing base (8da0631) to head (b4a7c67).
Report is 1 commits behind head on master.

❗ Current head b4a7c67 differs from pull request most recent head 402b5b1. Consider uploading reports for the commit 402b5b1 to get more accurate results

Files	Patch %	Lines
foqus_lib/framework/sampleResults/results.py	66.66%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1214      +/-   ##
==========================================
+ Coverage   38.54%   38.77%   +0.22%     
==========================================
  Files         164      164              
  Lines       37032    37044      +12     
  Branches     6132     6132              
==========================================
+ Hits        14274    14362      +88     
+ Misses      21619    21554      -65     
+ Partials     1139     1128      -11     

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[ksbeattie]

LGTM