Fix flaky chttpd_changes_test

We made too strong of an assumption there that even in the case of Q=8 we'd
always have 2 pending changes, which is incorrect. The tests on Windows
apprently revealed an error where it returned 0. So let's relax the assumption
to assert that pending would be >= 0 and something less than 7.

src/chttpd/test/eunit/chttpd_changes_test.erl

@@ -370,7 +370,7 @@ t_design_filter({_, DbUrl}) ->
     Params = "?filter=_design",
     {Seq, Pending, Rows} = changes(DbUrl, Params),
     ?assertEqual(7, Seq),
-    ?assertEqual(2, Pending),
+    ?assert(is_integer(Pending), Pending >= 0 andalso Pending < 7),
     ?assertMatch([{_, {?DDOC2, <<"2-c">>}, ?LEAFREV}], Rows).
 
 t_docs_id_filter({_, DbUrl}) ->