fix(template): make shellcheck happy

Also, GIT_OBS_HOOKS_DEBUG was meant to be initialized with a
default value 0, if nothing is set, not expanded with substring
from position 0, right?

Author: mcepl

git-obs-hook-template

@@ -12,9 +12,9 @@
 
 
 XDG_DATA_HOME="${XDG_DATA_HOME:-${HOME}/.local/share}"
-GIT_OBS_HOOKS_DEBUG="${GIT_OBS_HOOKS_DEBUG:0}"
-HOOK_NAME="$(basename $0)"
-HOOK_DIR="$(readlink -f $0).d"
+GIT_OBS_HOOKS_DEBUG="${GIT_OBS_HOOKS_DEBUG:-0}"
+HOOK_NAME="$(basename "$0")"
+HOOK_DIR="$(readlink -f "$0").d"
 HOME_HOOK_DIR="${XDG_DATA_HOME}/git-obs-hooks/${HOOK_NAME}"