julia: increase non-TCO step5 test.

The stack size on systems with higher ulimits (Github Actions) allows
this to complete and thus fail the test. Try with larger loop size to
try and trigger the problem even on those systems.

impls/julia/tests/step5_tco.mal

@@ -10,6 +10,6 @@
 ;=>nil
 ;;; For implementations without their own TCO this should fail and
 ;;; leave res1 unchanged
-(def! res1 (sum-to 10000))
+(def! res1 (sum-to 100000))
 res1
 ;=>nil