Makefile: Use chutney's latest default network

Use bridges+hs-v23 for "make test-network",
rather than using chutney's old default.

This change requires a recent version of chutney,
because the old bridges+hs-v23 did not work.
(See chutney's 33302 for details.)

Closes 28208.

changes/ticket28208

+  o Testing:
+    - Use the "bridges+hs-v23" chutney network flavor in "make test-network".
+      This test requires a recent version of chutney (mid-February 2020).
+      Closes ticket 28208.

src/test/include.am

@@ -64,7 +64,7 @@ TESTS += src/test/test src/test/test-slow src/test/test-memwipe \
 
 # run a quick test or two
 # this test only uses IPv4
-TEST_CHUTNEY_FLAVOR_QUICK = bridges+hs-v2
+TEST_CHUTNEY_FLAVOR_QUICK = bridges+hs-v23
 # only run if we can ping6 ::1 (localhost)
 TEST_CHUTNEY_FLAVOR_QUICK_IPV6 = client-ipv6-only-md