test: Increase offset to rendcache descriptor time

Slow system can sometime take more than 10 seconds to reach the test
callsite resulting in the unit test failing when using time in the future or
in the past.

Fixes #19465

Signed-off-by: David Goulet <dgoulet@torproject.org>

src/test/test_rendcache.c

@@ -17,8 +17,8 @@
 
 static const int RECENT_TIME = -10;
 static const int TIME_IN_THE_PAST = -(REND_CACHE_MAX_AGE + \
-                                      REND_CACHE_MAX_SKEW + 10);
-static const int TIME_IN_THE_FUTURE = REND_CACHE_MAX_SKEW + 10;
+                                      REND_CACHE_MAX_SKEW + 60);
+static const int TIME_IN_THE_FUTURE = REND_CACHE_MAX_SKEW + 60;
 
 static rend_data_t *
 mock_rend_data(const char *onion_address)