GH-50004: [CI][Python] Revert pinning miniforge

[adamreeve]

Rationale for this change

Undoes pinning the miniforge version, which is no longer required because miniforge now uses mamba 2.9.0, which includes the fix for mamba-org/mamba#4274. Unpinning allows us to benefit from improvements in new versions. See #49998 for context.

What changes are included in this PR?

Use the latest version of miniforge when installing it in Docker, instead of 26.1.1-3.

Are these changes tested?

They will be once CI runs 😄

Are there any user-facing changes?

No

Was AI used for this PR?

In accordance to the AI generation guidelines, please disclose below whether and how AI was used in this PR.

PR code and description written by:

• Human
• AI

Reviewed before submission by:

• Human
• AI
• Not reviewed

• GitHub Issue: [CI][Python] Revert pinning miniforge once mamba solver issue is resolved #50004

[github-actions]

⚠️ GitHub issue #50004 has been automatically assigned in GitHub to PR creator.

[Copilot]

Copilot review overview

🟢 Approval recommended

The focused CI configuration change correctly removes the temporary pin after the upstream fix.

Review effort: Balanced
Findings: None

What changed in this PR

Updates the Conda CI image to use the latest Miniforge release now that the mamba solver regression is fixed.

Changes:

• Removes the temporary Miniforge pin and explanatory comments.
• Installs the latest Miniforge release.

File	Description
ci/​docker/​conda.dockerfile	Switches Miniforge installation from version 26.1.1-3 to latest.

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[kou]

+1

Could you also unpin

arrow/ci/docker/ubuntu-22.04-verify-rc.dockerfile

Line 33 in bbbc06f

RUN /arrow/ci/scripts/install_conda.sh miniforge3 26.1.1-3 /opt/conda && \

too?

It was added by #50649 . @tadeja Can we unpin it too?

[Copilot]

Copilot review overview

🟢 Approval recommended

The focused changes consistently remove the temporary pin after the fixed Mamba version was released.

Review effort: Balanced
Findings: None

[raulcd]

@github-actions crossbow submit verify-rc-source-*conda-*amd64

[github-actions]

Revision: fadee49

Submitted crossbow builds: ursacomputing/crossbow @ actions-6985bb8d80

Task	Status
verify-rc-source-cpp-linux-conda-latest-amd64
verify-rc-source-integration-linux-conda-latest-amd64
verify-rc-source-python-linux-conda-latest-amd64
verify-rc-source-ruby-linux-conda-latest-amd64

[raulcd]

@github-actions crossbow submit verify-rc-source-*-ubuntu-22.04-amd64

[raulcd]

sorry, was the second set of crossbow jobs not the first one :) I still require some coffee today.

[github-actions]

Revision: fadee49

Submitted crossbow builds: ursacomputing/crossbow @ actions-9eadb49b17

Task	Status
verify-rc-source-cpp-linux-ubuntu-22.04-amd64
verify-rc-source-integration-linux-ubuntu-22.04-amd64
verify-rc-source-python-linux-ubuntu-22.04-amd64
verify-rc-source-ruby-linux-ubuntu-22.04-amd64

[raulcd]

This can be merged as the previous failing job failure is now passing.