Add missing line separator (model-checking#232)

Fix a typo introduced in model-checking#229 that prevents `kani-args` from getting
passed to the `kani` command.

This was discovered by @tengjiang (see
model-checking#231).

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

Author: zhassan-aws

scripts/run-kani.sh

@@ -288,7 +288,7 @@ main() {
             # Run verification for all harnesses (not in parallel)
             echo "Running Kani verify-std command..."
             "$kani_path" verify-std -Z unstable-options ./library \
-                $unstable_args
+                $unstable_args \
                 $command_args \
                 --enable-unstable \
                 --cbmc-args --object-bits 12