git 2.45.1 and vcpkg 2024.04.26

[rcoup]

Description

Update Git to 2.45.1 (#993) and vcpkg to 2024.04.26.

Spatialite caused a segfault updating to the latest on macOS+Linux, so I've left it at the previous release. Nothing obvious in the changelog post-5.1.0, but I haven't bisected or tried trunk from upstream.

A couple of minor tweaks for build/test robustness.

Related links:

Builds on & replaces #993

Checklist:

• [x] Have you reviewed your own change?
• [x] Have you included test(s)?
• [ ] Have you updated the changelog?