[DEV-1674][Back End] Upgrade to Python 3

[muhsen84]

Before submitting a pull request make sure you have:

• The pull request title contains a meaningful title
• At least skimmed through the coding conventions used in the project
• Checked the code with flake8
• Performed a self-review of my own code
• The code is commented, particularly in hard-to-understand areas
• The documentation associated was created or updated
• The changes generate no new warnings
• Add tests that prove the change is effective or that the feature works
• New and existing unit tests pass locally with the changes
• Any dependent changes have been merged and published in downstream modules

What is the purpose of your pull request?

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (code refactoring or improvement in some way a functionality)
• New feature (non-breaking change which adds functionality)
• Hot Fix (Breaking change)
• Release (new release version)

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Contents of the Pull Request

• Upgrade to Python 3
  • We used 2to3 tool for an initial upgrade
  • We reviewed the upgraded code and enhanced it

Jira Tasks Associated

This PR is associated with the following Jira Tasks:

DEV-1674 [CrowdSurf] Upgrade the codebase to Python 3

How Has This Been Tested? (Required)

Not tested yet because the Dev environment is not ready yet and it is too risky to deploy it to production without proper testing