tests/upgrade: Re-add "epubreader" to tested apps

When updating Nextcloud apps in 989a136,
I actually forgot about the assertion on epubreader 1.4.3, which was
exactly there so that we re-add epubreader to our tests.

I haven't run the full test yet, but according to some comment[1] in a
related issue, the issue has been fixed.

This fixes evaluation of our upgrade test.

[1]: e-alfred/epubreader#18 (comment)

Signed-off-by: aszlig <aszlig@nix.build>

tests/upgrade.nix

@@ -82,9 +82,6 @@ import ./make-test.nix (pkgs: {
         # https://github.com/nextcloud/user_oidc/issues/90
         (assert nc19apps.user_oidc.version == "0.2.1"; "user_oidc")
 
-        # https://github.com/e-alfred/epubreader/issues/22
-        (assert nc19apps.epubreader.version == "1.4.3"; "epubreader")
-
         # These apps have non-deterministic download URLs
         "occweb"
         "quicknotes"