Re-fix building of XAP keymaps on master/develop (#25892)

.github/workflows/ci_build_major_branch_keymap.yml

@@ -106,7 +106,7 @@ jobs:
         run: |
           export NCPUS=$(( $(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || getconf _NPROCESSORS_ONLN 2>/dev/null) -1 ))
           targets=$(jq -r '.["${{ matrix.target }}"].targets' targets.json | tr ' ' '\n' | sort)
-          if [[ -z ${targets} ]]; then
+          if [ -z "${targets}" ]; then
             echo "Zero build targets detected"
             exit 0
           fi