Test on the latest stable perl 5.40 too

Author: Eugen Konkov

.github/workflows/linux.yml

@@ -16,6 +16,7 @@ jobs:
           - '5.32'
           - '5.34'
           - '5.36'
+          - '5.42'
     container:
       image: perl:${{ matrix.perl-version }}
     steps: