Replace deprecated append method with concat

[hurrifan1]

Replaced the deprecated and recently removed Dataframe.append() method with the recommended Pandas.concat(). Dataframe.append() has been deprecated for a while and was removed in the most recent Pandas 2.0.0 release. See Pandas issue here.

There was not an existing issue for this, let me know if I should make one first for tracking purposes.

Status

[ ] Under development
[X] Waiting for code review
[ ] Waiting for merge

Information

[ ] Contains breaking changes
[ ] Contains new API(s)
[ ] Contains documentation
[ ] Contains test
[ ] Contains examples

To-do list

No todos

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