github actions: add 5.40.0

Author: eserte

.github/workflows/test.yml

@@ -101,6 +101,7 @@ jobs:
           - image: perl:5.22.4-stretch
           - image: perl:5.36.0-bullseye
           - image: perl:5.38.0-bookworm
+          - image: perl:5.40.0-bookworm
           ## use debian:* images only if there's no suitable perl:* image
           #- image: debian:bookworm