Log Message:
devel/gitui: update to 0.26.3

[0.26.3] - 2024-06-02
Breaking Changes
Theme file format

note: this actually applied to the previous release already: 0.26.2
Ratatui (upstream terminal rendering crate) changed its serialization format
for Colors. So the theme files have to be adjusted.

selection_fg: Some(White) -> selection_fg: Some("White")

but this also allows us now to define colors in the common hex format:

selection_fg: Some(Rgb(0,255,0)) -> selection_fg: Some("#00ff00")

Checkout THEMES.md for more info.

Added
 - due to github runner changes, the regular mac build is now arm64, so we added
   support for intel x86 apple build in nightlies and releases (via separat
   artifact)
 - support BUILD_GIT_COMMIT_ID enabling builds from git archive generated source
   tarballs or other outside a git repo [@alerque] (#2187)

Fixes
 - update yanked dependency to libc to fix building with --locked.
 - document breaking change in theme file format.