Keep test spicy.rt.time working for the next 200 years.

This test still compares the current time against hardcoded times to
check ordering. Extend the upper value so this test passes for the next
~200 years.

(cherry picked from commit 93c2cc8)

tests/spicy/rt/time.spicy

@@ -6,4 +6,4 @@ module Test;
 import spicy;
 
 global t = spicy::current_time();
-assert t > time(1564617600) && t < time(1735689600);
+assert t > time(1000000000) && t < time(8000000000);