Fix bug in env_checker.py bounds warning message

[Gabo-Tor]

Description

• Fix bug where Gym Environment Checker does not output the correct warning message when dealing with observation spaces that have different upper and different lower bounds

• Update test_env_checker.py with more comprehensive tests

Motivation and Context

closes #1632

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

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• I have updated the tests accordingly (required for a bug fix or a new feature).
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[araffin]

Thanks for the PR =), unfortunately your solution only worked with 1D arrays.
As you use master branch to create the PR, I couldn't push my edits, I created a new branch here: #1638

It would be helpful if you could review it ;)

[Gabo-Tor]

Thanks for the PR =), unfortunately your solution only worked with 1D arrays. As you use master branch to create the PR, I couldn't push my edits, I created a new branch here: #1638

It would be helpful if you could review it ;)

Hey there! Thanks for your feedback =) I'm sorry about missing the multiple dimensions in my solution. I'll definitely take a look at the new branch (#1638). I hope to do better on my next PR! 🙌