Skip planned+prerelease versions in active Python releases table

[hugovk]

Description

• Skip status=planned releases (currently 3.16) in the active releases table. This is an end-user facing page, so a single 3.15 pre-release is enough here. And there's nothing to download yet for 3.16.
• https://devguide.python.org/versions/ aimed at developers does include 3.16.
• Let's not worry that the SVG chart includes 3.16, it's served from the devguide.

Before:

https://www.python.org/downloads/

After:

3.16 will be status=prerelease when its development starts in main in May, and before the first 3.16 alpha in October. Skip that too.

[Copilot]

Pull request overview

This PR updates the “Active Python releases” table rendering so that release cycles marked as status=planned are omitted from the end-user downloads page, avoiding listing versions that have nothing downloadable yet.

Changes:

• Exclude planned release cycles from the render_active_releases() inclusion tag output.
• Extend template-tag tests to include a mocked planned release cycle (3.16) and assert it is not displayed.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
apps/downloads/templatetags/download_tags.py	Skips status == "planned" entries when building the active releases list.
apps/downloads/tests/test_template_tags.py	Adds mocked 3.16 planned cycle and a test ensuring planned releases are excluded.

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[hugovk]

@JacobCoffee Please could you check this? I saw people in the Python Discord getting confused by 3.16 in the list.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[JacobCoffee]

@hugovk feel free to ping earlier, didnt see this. my gh notifications lately are bonkers 😵‍💫

[hugovk]

Will do! Although I forgot about it until I saw the Python Discord confusion :)