Update memberlist to 0.3.1 (#12042)

Author: Chris S. Kim

Diff for: .changelog/12042.txt

@@ -0,0 +1,4 @@
+```release-note:bug
+memberlist: fixes a bug which prevented members from joining a cluster with
+large amounts of churn [[GH-253](https://github.com/hashicorp/memberlist/issues/253)]
+```

Diff for: go.mod

@@ -49,7 +49,7 @@ require (
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/hashicorp/hcl v1.0.0
 	github.com/hashicorp/hil v0.0.0-20200423225030-a18a1cd20038
-	github.com/hashicorp/memberlist v0.3.0
+	github.com/hashicorp/memberlist v0.3.1
 	github.com/hashicorp/net-rpc-msgpackrpc v0.0.0-20151116020338-a14192a58a69
 	github.com/hashicorp/raft v1.3.3
 	github.com/hashicorp/raft-autopilot v0.1.5

Diff for: go.sum

@@ -281,8 +281,9 @@ github.com/hashicorp/logutils v1.0.0/go.mod h1:QIAnNjmIWmVIIkWDTG1z5v++HQmx9WQRO
 github.com/hashicorp/mdns v1.0.1/go.mod h1:4gW7WsVCke5TE7EPeYliwHlRUyBtfCwuFwuMg2DmyNY=
 github.com/hashicorp/mdns v1.0.4 h1:sY0CMhFmjIPDMlTB+HfymFHCaYLhgifZ0QhjaYKD/UQ=
 github.com/hashicorp/mdns v1.0.4/go.mod h1:mtBihi+LeNXGtG8L9dX59gAEa12BDtBQSp4v/YAJqrc=
-github.com/hashicorp/memberlist v0.3.0 h1:8+567mCcFDnS5ADl7lrpxPMWiFCElyUEeW0gtj34fMA=
 github.com/hashicorp/memberlist v0.3.0/go.mod h1:MS2lj3INKhZjWNqd3N0m3J+Jxf3DAOnAH9VT3Sh9MUE=
+github.com/hashicorp/memberlist v0.3.1 h1:MXgUXLqva1QvpVEDQW1IQLG0wivQAtmFlHRQ+1vWZfM=
+github.com/hashicorp/memberlist v0.3.1/go.mod h1:MS2lj3INKhZjWNqd3N0m3J+Jxf3DAOnAH9VT3Sh9MUE=
 github.com/hashicorp/net-rpc-msgpackrpc v0.0.0-20151116020338-a14192a58a69 h1:lc3c72qGlIMDqQpQH82Y4vaglRMMFdJbziYWriR4UcE=
 github.com/hashicorp/net-rpc-msgpackrpc v0.0.0-20151116020338-a14192a58a69/go.mod h1:/z+jUGRBlwVpUZfjute9jWaF6/HuhjuFQuL1YXzVD1Q=
 github.com/hashicorp/raft v1.1.0/go.mod h1:4Ak7FSPnuvmb0GV6vgIAJ4vYT4bek9bb6Q+7HVbyzqM=