Add multiple packages to apt.txt to check if all are parsed and installed

tests/venv/apt-packages/apt.txt

@@ -1,3 +1,8 @@
 # testing to skip comments in this file
 
 gfortran
+
+# testing to see if all packages get installed
+rolldice
+moo
+

tests/venv/apt-packages/verify

@@ -1,3 +1,5 @@
 #!/bin/bash
 set -euo pipefail
 which gfortran
+which rolldice
+which sl