[ Reason ]
Package FTBFS in some environments (for example, but not only, single-cpu systems).

[ Impact ]
Somebody who builds the package from source may find that the package does not build
for no good reason.

[ Tests ]
I've checked that after disabling the flaky test, the package builds ok on the systems
where it used to fail.

[ Risks ]
Very low. No real code changes, as we are just disabling a test. The test has been
implicitly acknowledged by upstream to be flaky, but no official fix has been merged yet.

[ Checklist ]
   [X] *all* changes are documented in the d/changelog
   [X] I reviewed all changes and I approve them
   [X] attach debdiff against the package in (old)stable
   [X] the issue is verified as fixed in unstable

[ Changes ]
Disable flaky test TestLoadingExpired.

[ Other info ]
Change is trivial so I will upload after sending this report.