ci: bump Go to 1.24 for vexctl so it loads on macOS (LC_UUID)

The `test (macos-latest)` matrix job installs vexctl via `go install` and runs
tests/e2e_vex.rs against it. The macОS-latest runner image (Sequoia+) has a
dyld that refuses to load a Mach-O binary lacking an LC_UUID load command, and
Go's linker only began emitting one in 1.24 — so the 1.22-built vexctl crashed
on launch ("dyld: missing LC_UUID load command in .../vexctl") and every
e2e_vex assertion failed with "vexctl rejected the document". Environmental,
not a code regression (ubuntu/windows were unaffected); the shared matrix pin
just needed bumping.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mikolalysenko

.github/workflows/ci.yml

@@ -99,10 +99,15 @@ jobs:
         # validates the output with vexctl when it's on PATH. vexctl is
         # a Go binary distributed via `go install`. Setting up Go here
         # is the cheapest way to give every test job a usable vexctl.
+        # Go must be >= 1.24: its linker only began emitting an LC_UUID load
+        # command then, and the macOS-latest runner's dyld (Sequoia+) refuses
+        # to load a Mach-O binary without one ("missing LC_UUID load command"),
+        # so a 1.22-built vexctl crashes on launch and every e2e_vex assertion
+        # fails. ubuntu/windows are unaffected, but the matrix shares this pin.
         # SHA pin resolved from `gh api repos/actions/setup-go/git/refs/tags/v6.4.0`.
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
-          go-version: '1.22'
+          go-version: '1.24'
           cache: false
 
       - name: Install vexctl