Add dependabot and cap dependencies

[jdeschamps]

Description

To ensure that users can create functioning environments, this PR adds an upper version to all main dependencies and adds a dependabot to update them.

Changes Made

• Added: dependabot.yml
• Modified: pyproject.toml

Note

We will need to update the conda-forge feedstock to reflect the new dependencies.

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Please ensure your PR meets the following requirements:

• Code builds and passes tests locally, including doctests
• New tests have been added (for bug fixes/features)
• Pre-commit passes
• PR to the documentation exists (for bug fixes / features)