Updated AWSSDK.S3 to 4.0

[mdupras]

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Description

Updated the AWSSDK.S3 to 4.0 release and fix the compilation issue.
Now metadata.LastModified can be null, I don't think it's like to happen in this scenario, but if it does the default Date is Now to assume the Image needs to be refreshed.

[dlemstra]

The 3.x range is also still being updated but I think we can upgrade to the 4.x range because we don't need net3.5 support

[JimBobSquarePants]

@dlemstra I'm not convinced we can update yet.

By doing so we introduce a breaking change via the dependency. Normally that would require a major version on our part.

@mdupras we have multiple failing tests here. Could you please have a look?

[JimBobSquarePants]

Altering global behavior for transitive dependency does not appear be a prudent. It would be more appropriate to update the code to accommodate changes in behavior.

[mdupras]

@dlemstra I'm not convinced we can update yet.

By doing so we introduce a breaking change via the dependency. Normally that would require a major version on our part.

@mdupras we have multiple failing tests here. Could you please have a look?

Thanks, I'm looking into it a bit. Managed to get the test failing locally, I'll try to take some time to investigate that soon!