Use the absolute path to avoid command not found on GitHub Actions

```patch
diff --git a/.chezmoiscripts/darwin/defaults.sh b/.chezmoiscripts/darwin/defaults.sh
new file mode 100755
index 0000000000000000000000000000000000000000..1998ac1
--- /dev/null
+++ b/.chezmoiscripts/darwin/defaults.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+defaults write -g ApplePressAndHoldEnabled -bool false
/tmp/1226643682.defaults.sh: line 2: defaults: command not found
chezmoi: .chezmoiscripts/darwin/defaults.sh: exit status 127
```

Author: mono0x

src/.chezmoiscripts/darwin/run_onchange_defaults.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-defaults write -g ApplePressAndHoldEnabled -bool false
+/usr/bin/defaults write -g ApplePressAndHoldEnabled -bool false