fix: add git to devbox packages to prevent init_hook failure on macOS

[lucastvms]

Added git to devbox.json to fix a failure in the init_hook. (devbox add git)

The issue:

Without git in the devbox environment, git rev-parse --show-toplevel fails, causing $GOBIN to default to /bin. On macOS, writing to /bin is forbidden (SIP), resulting in an operation not permitted error during the go install step.

Proof of Fix:

# Error before fix:
error: tool 'git' not found
sigs.k8s.io/cloud-provider-kind: copying ... exe/a.out: open /bin/cloud-provider-kind: operation not permitted

# Success after 'devbox add git':
lucas@MacBook-Pro-de-Lucas devops-directive-kubernetes-course % devbox shell
Info: Ensuring packages are installed.
✓ Computed the Devbox environment.
Starting a devbox shell...
(devbox) lucas@MacBook-Pro-de-Lucas devops-directive-kubernetes-course %