feat: All tests run in a child process now.

testtest.c

@@ -1,13 +1,17 @@
 #include "set.h"
+#include <unistd.h>
+
 #include "set_asserts.h"
 
 int fac(int n)
 {
-    if (n <= 1)
+    if (n == 1)
         return 1;
     return n * fac(n - 1);
 }
 
+void heavy_load() { sleep(5); }
+
 TEST(Faculty_Basic)
 {
     ASSERT_EQ(fac(5), 120);