infra: drop support for Python 3.9

[math411]

Issue #, if available:

Description of changes:
This PR serves to allow Braket to start dropping support for Python 3.10. Dependencies have begun to do so. This does not serve as an immediate action but a look into what changes would take place to achieve dropped support.

Notable packages:

• https://github.com/numpy/numpy/releases/tag/v2.1.1
• PennyLaneAI/pennylane@713a33d (this is expected in their next Pypi release)
• https://github.com/scipy/scipy/releases/tag/v1.14.0
• https://github.com/google/jax/releases/tag/jax-v0.4.31

I have added comments within https://github.com/amazon-braket/amazon-braket-examples/blob/main/requirements.txt to highlight these during dependency upgrades.

Testing done:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e4e0c9f) to head (939c053).

Additional details and impacted files

@@             Coverage Diff             @@
##           ruff_test     #1031   +/-   ##
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  Coverage     100.00%   100.00%           
===========================================
  Files            135       135           
  Lines           8998      8989    -9     
  Branches        2020      2020           
===========================================
- Hits            8998      8989    -9     

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[rmshaffer]

@math411 Could you provide some more background/context on why we want to do this, given that Python 3.9 is not EOL until October 2025?

[math411]

@rmshaffer added in some context.