Import pandas through pyomo.common.dependencies

[jsiirola]

Fixes # .

Summary/Motivation:

This updates examples to import pandas through pyomo.common.dependencies.

This change was motivated by a deprecation warning that pandas emits upon import that was breaking the Pyomo package layout tests.

Changes proposed in this PR:

• Import pandas through pyomo.common.dependencies and not directly

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[michaelbynum]

Looks like pyros tests are failing.

[mrmundt]

Looks like pyros tests are failing.

They are failing on both this and #3102 , and those two don't appear to have anything in common. I am running a different test on Jenkins to see if this is just in main now somehow.

[michaelbynum]

Thanks, @mrmundt. I'm guessing there is some subsolver issue, but I can't tell from the logs.