debian: add more scenarios to dep8 tests

We are now calling two API endpoints on the dep8 tests.
Those endpoints don't trigger any network call and their
main use is to verify if any python3-apt change would change
the way we interact with that library, as those API endpoints
heavily rely on apt functionality.

debian/tests/usage

@@ -2,5 +2,11 @@
 
 set -ex
 
-ua --help | grep --silent services
-ua version
+pro --help | grep --silent services
+pro version
+
+# These calls are used to ensure that the
+# way we interact with APT is still working
+# if python3-apt receives an upgrade
+pro api u.pro.packages.summary.v1
+pro api u.pro.packages.updates.v1