Remove support for MongoDB 4.0

[mtrezza]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

MongoDB 4.0 reached its EOL in April 2022.

Feature / Enhancement Description

Remove support for MongoDB 4.0:

• Remove related tests (restricted to MongoDB version)
• Remove from CI workflow

Example Use Case

n/a

Alternatives / Workarounds

n/a

[parse-github-assistant]

Thanks for opening this issue!

• 🎉 We are excited about your ideas for improvement!

[parseplatformorg]

🎉 This change has been released in version 6.0.0-alpha.6

[parse-github-assistant]

The label state:released-alpha cannot be used in combination with state:breaking.

[parseplatformorg]

🎉 This change has been released in version 6.0.0-beta.1

[parseplatformorg]

🎉 This change has been released in version 6.0.0