CI: Update and cleanup workflow scripts

Fix an infinite loop if a shim is symlinked to and called from a different location

Signed-off-by: Edgar Ramírez-Mondragón <edgarrm358@gmail.com>

Since 14.07.2025, Anaconda requires accepting the new TOS upon installation
that limit eligibility for free use

[no ci]

Adds latest miniforge releases 25.9.1-0, 25.11.0-1

Adds latest miniforge releases 25.9.1-0, 25.11.0-1.

Skips 25.11.0-0 due to a regression reported in the release notes of
miniforge3-25.11.0-1.

Ref: https://github.com/conda-forge/miniforge/releases/tag/25.11.0-1

At least under Python 3.14, this quickly fails without lxml[html_clean]
installed explicitly.

Co-authored-by: binbjz <binbjz@gmail.com>

Citing https://www.postgrespro.ru/list/id/E1kfzRR-0001EH-Ph@gemulon.postgresql.org
fixing the same problem:
We previously put the -isysroot switch only into CPPFLAGS, theorizing
that it was only needed to find the right copies of include files.
However, it seems that we also need to use it while linking programs,
to find the right stub ".tbd" files for libraries.  We got away
without that up to now, but apparently that was mostly luck.  It may
also be that failures are only observed when the Xcode version is
noticeably out of sync with the host macOS version; the case that's
prompting action right now is that builds fail when using latest Xcode
(12.2) on macOS Catalina, even though it's fine on Big Sur.

Specifically, the problem arises for `preadv' and `pwritev' (new in MacOS 11 Big Sur) when building with XCode 12.4 (supporting Big Sur) in MacOS 10.15 Catalina.

Bumps the github-actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

> The macOS 13 Ventura based runner images will begin deprecation on September 22nd and will be fully unsupported by December 4th for GitHub and ADO.

https://github.com/actions/runner-images/issues/13046

Signed-off-by: Edgar Ramírez Mondragón <edgarrm358@gmail.com>

https://www.gnu.org/server/mirror.html advises
to use http://ftpmirror.gnu.org/
for automatic mirror selection

Use tclConfig.sh/tkConfig.sh for future-proofing
3.14.0 doesn't detect Tcl/Tk with external libtommath, have to do it ourselves

---------

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>