Upgrade to numpy 2 in conda

[tobiasdiez]

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

• Update conda to use Python 3.12, drop 3.9 and 3.10 #39164

[github-actions]

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[user202729]

After this is merged, what's the plan for support of numpy < 2? (if yes we still need to test both somehow? The semantic for e.g. copy=False is slightly different)

[tobiasdiez]

This is done as part of #38749.

[tornaria]

After this is merged, what's the plan for support of numpy < 2? (if yes we still need to test both somehow? The semantic for e.g. copy=False is slightly different)

Since numpy 1.26 is EOL on 17 Sep 2025, it may not be necessary to test it beyond sagemath 10.6.