Avoid IPv4 when unsupported (#37)

Skip a test which checks that binding to `anyIPv4` doesn't bind to an
IPv6 address when IPv4 isn't supported.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f4e4dc1..32eca00 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,5 @@
+## 3.1.1-dev
+
 ## 3.1.0
 
 * Add `HttpMultiServer.bindSecure` to match `HttpMultiServer.bind`.
diff --git a/pubspec.yaml b/pubspec.yaml
index af58e87..c03d358 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: http_multi_server
-version: 3.1.0
+version: 3.1.1-dev
 
 description: >-
   A dart:io HttpServer wrapper that handles requests from multiple servers.
diff --git a/test/http_multi_server_test.dart b/test/http_multi_server_test.dart
index 96ffa23..3a0bdcf 100644
--- a/test/http_multi_server_test.dart
+++ b/test/http_multi_server_test.dart
@@ -296,6 +296,7 @@
     });
 
     test('listens on specified hostname', () async {
+      if (!await supportsIPv4) return;
       final server =
           await HttpMultiServer.bindSecure(InternetAddress.anyIPv4, 0, context);
       server.listen((request) {
@@ -303,10 +304,8 @@
         request.response.close();
       });
 
-      if (await supportsIPv4) {
-        expect(client.read(Uri.https('127.0.0.1:${server.port}', '')),
-            completion(equals('got request')));
-      }
+      expect(client.read(Uri.https('127.0.0.1:${server.port}', '')),
+          completion(equals('got request')));
 
       if (await supportsIPv6) {
         expect(client.read(Uri.https('[::1]:${server.port}', '')),