fix: remove future usages

[UsamaSadiq]

Description

• future package had a security vulnerability which was pointed out some time ago
• Remove usages of the package future and its dependency from the requirements.

Testing

• This change will impact the codejail code execution of the students assessments too so it will be tested using sandboxes first before merging.
• Tested the change using the draft PR Usamasadiq/test codejail upgrade openedx-platform#31589 in edx-platform.
• All the sample problems from the Code Jail Test Problems[Accessible to 2u-internal only] are working fine.
• Sandbox Course tested for all the codejail problems.

[connorhaugh]

@UsamaSadiq what is your analysis of the security risks of removing this package without replacing it? It seems like we should just replace python 2 code with python 3 code, so it is ok? I just want to ensure future isn't there for security reasons.

[UsamaSadiq]

We don't need to replace future package with any other since it was only used in Python 2 which we've already dropped support for. future wasn't used for any security reasons rather it was used in Python 2 only to use some functions from Python 3.

[connorhaugh]

Thanks, after looking more into the package I agree.