test.sh: fix removal of test output files

test.sh

@@ -31,7 +31,7 @@ for day in day*; do
 	for solution in "$day"/*; do
 		echo -n "$solution... "
 		solution_output=$(mktemp)
-		trap "rm $solution_output" EXIT
+		trap "rm -f '$solution_output'" EXIT
 		run_solution "$solution" > "$solution_output"
 
 		if ! diff -u "$expected" "$solution_output"; then
@@ -48,5 +48,7 @@ for day in day*; do
 		else
 			echo ok
 		fi
+
+		rm "$solution_output"
 	done
 done