ci: fix mangled python image tag on release/26.06

[rgsl888prabhu]

Three fixes for the release/26.06 release-prep regression:

1. Restore the python image tag — nightly-summary.yaml:63 and build.yaml:315 had python:26.06-slim, which doesn't exist on Docker Hub. Reverted to python:3.14-slim (matches main). Unblocks the nightly-summary and build-summary jobs.

2. Scope the version-bump regex — ci/release/update-version.sh:142 was matching any :N.N- in workflow files, which is what mangled the python image during release prep. Scoped to lines containing rapidsai/ so unrelated images are left alone.

3. Drop dead routing-example.ipynb sed call — ci/release/update-version.sh was sed-ing a file that no longer exists, erroring on every release-prep run. The routing docs currently have no main-branch links so the line was a no-op even before the file was removed.

Verified by running ./ci/release/update-version.sh --run-context=release 99.99.00 in a throwaway worktree — only the four rapidsai/ci-conda:NN.NN-latest lines bump, python:3.14-slim is untouched, and no errors are emitted.

Same regex bug exists on main; this PR carries the fix on release/26.06 so patch releases off this branch won't re-mangle. A separate cherry-pick to main is straightforward.

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• ci/release/update-version.sh

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• ci/release/update-version.sh

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📝 Walkthrough

Walkthrough

This PR updates two CI workflow jobs to use the python:3.14-slim container instead of python:26.06-slim, and scopes ci/release/update-version.sh’s image tag prefix rewrite to only affect rapidsai/ images and redirects a docs link rewrite to docs/cuopt/source/faq.rst.

Changes

CI Python Runtime Updates & Release Script

Layer / File(s)	Summary
Python runtime container image updates .github/workflows/build.yaml, .github/workflows/nightly-summary.yaml	The build-summary job (line 315) and nightly-summary job (line 63) container images are updated from python:26.06-slim to python:3.14-slim.
Release script: scope image tag rewrite & docs link target ci/release/update-version.sh	The sed substitution that rewrites CI image tag prefixes is now scoped to lines containing rapidsai/, replacing tag prefixes with ${NEXT_SHORT_TAG}- only for rapidsai/ image references (lines ~141-143). In release run-context, the docs link rewrite target is changed to docs/cuopt/source/faq.rst (lines ~152-153).

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🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main fix: restoring the mangled Python image tag on the release/26.06 branch.
Description check	✅ Passed	The description clearly explains all three fixes: Python image tag restoration, regex scoping, and removal of dead code, with verification details.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[bdice]

Please fix ci/release/update-version.sh in this PR. We may need to rerun that script as a part of manual forward-merges from release/26.06, so landing a fix for the script on release/26.06 is needed.

[bdice]

Meant to request changes for the above, accidentally hit wrong button

[rgsl888prabhu]

/merge