ci: install expect and update printf usage

- printf -v is non-standard, use var=$(printf) instead.
- expect is not installed in the runner. install it manually

Signed-off-by: greatbridf <greatbridf@icloud.com>

.github/workflows/test-build.yaml

@@ -31,7 +31,7 @@ jobs:
       - name: Setup QEMU
         run: |
           sudo apt-get update
-          sudo apt-get install -y qemu-system-${{ matrix.arch }} qemu-kvm
+          sudo apt-get install -y qemu-system-${{ matrix.arch }} qemu-kvm expect
 
       - name: Configure
         run: ./configure

script/test.sh

@@ -9,7 +9,7 @@ die() {
 }
 
 runcmd() {
-    printf -v _cmd "%q" "$*"
+    _cmd=$(printf "%q" "$*")
 
     cat <<EOF
     expect {