GH1352 Add passing a dict with integer for pd.to_datetime

[loicdiridollou]

• Closes pd.to_datetime from a dict where one of the field is an int #1352
• Tests added: Please use assert_type() to assert the type of any return value

• fix for the nightly CI with pandas

[loicdiridollou]

/pandas_nightly

[Dr-Irv]

thanks for also doing the Pandas4Warning thing to fix nightly. I was going to do that when they fix that one other issue - still waiting for that.

[Dr-Irv]

thanks @loicdiridollou