test(ip): require command for route replace test

Found while testing macOS in CI.

Author: scop

test/t/test_ip.py

@@ -10,6 +10,6 @@ def test_1(self, completion):
     def test_2(self, completion):
         assert completion
 
-    @pytest.mark.complete("ip route replace ")
+    @pytest.mark.complete("ip route replace ", require_cmd=True)
     def test_r_r(self, completion):
         assert completion

test/test-cmd-list.txt

@@ -149,6 +149,7 @@ inotifywait
 inotifywatch
 interdiff
 ionice
+ip
 ipcalc
 iperf
 iperf3