MAINT: Update version of pixi-lock action

[VeckoTheGecko]

There have been a few improvements to the action since last time.

Doing a git log...

commit 9a2866f8258b87a3c616d5ad7d51c6cd853df78b
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Thu Jan 22 15:21:08 2026 +0100

    MAINT: Add clear-cache job (#12)

commit db461d0c51291113d871d597ae4702135b892d2f
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Thu Jan 22 14:43:20 2026 +0100

    bugfix: Enable crossOsArchive when checking for existing cache (#11)

commit 82087290114bffa037dc527b2afc3d1c797eda8f
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Tue Jan 20 17:15:32 2026 +0100

    Update README (#10)

commit 36b222f41a5b8e6a2efd83de9dc3eb37f535882f
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Tue Jan 20 17:11:41 2026 +0100

    Disallow empty cache-key (#8)

commit 79d515de8aa310366c51987054450dd83758da18
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Tue Jan 20 17:11:28 2026 +0100

    Update README (#9)

commit 249335d92109b0d797341cbfee3af8d07489ade9
Author: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Tue Jan 20 14:09:11 2026 +0100

    Add sha pins (#7)

commit 5cbd7a155fa24aa0711ec0a9aad9ede0819e84a1
Author: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date:   Tue Jan 20 10:05:10 2026 +0100

    Update README

[VeckoTheGecko]

ci failure unrelated