test: update test-run

Add 'decimal' to a built-in modules list to preserve
package.loaded.decimal when pretest_clean is set in suite.ini.

Needed for #692.

test-run @ 5c71ff67

-Subproject commit 27aebd93121769820c0983842b447642460a8aac
+Subproject commit 5c71ff6707a96e9e06869b0336a153ae45456d77