Update ristretto to bring in jemalloc-stats fix (#7122)

Use the latest ristretto to bring in the jemalloc-stats fix.

(cherry picked from commit 188711a)

go.mod

@@ -21,7 +21,7 @@ require (
 	github.com/dgraph-io/gqlgen v0.13.2
 	github.com/dgraph-io/gqlparser/v2 v2.1.1
 	github.com/dgraph-io/graphql-transport-ws v0.0.0-20200916064635-48589439591b
-	github.com/dgraph-io/ristretto v0.0.4-0.20201205013540-bafef7527542
+	github.com/dgraph-io/ristretto v0.0.4-0.20201207174236-c72a155bcf05
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible
 	github.com/dgrijalva/jwt-go/v4 v4.0.0-preview1
 	github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13

go.sum

@@ -126,8 +126,9 @@ github.com/dgraph-io/gqlparser/v2 v2.1.1 h1:OBGI6VR+WcegjDB3JdNPMpKpEtITHWzgmiCX
 github.com/dgraph-io/gqlparser/v2 v2.1.1/go.mod h1:MYS4jppjyx8b9tuUtjV7jU1UFZK6P9fvO8TsIsQtRKU=
 github.com/dgraph-io/graphql-transport-ws v0.0.0-20200916064635-48589439591b h1:PDEhlwHpkEQ5WBfOOKZCNZTXFDGyCEWTYDhxGQbyIpk=
 github.com/dgraph-io/graphql-transport-ws v0.0.0-20200916064635-48589439591b/go.mod h1:7z3c/5w0sMYYZF5bHsrh8IH4fKwG5O5Y70cPH1ZLLRQ=
-github.com/dgraph-io/ristretto v0.0.4-0.20201205013540-bafef7527542 h1:Yya3DAZRF8ibfavFQQysegFbPJQ8plpta39uev0lw1I=
 github.com/dgraph-io/ristretto v0.0.4-0.20201205013540-bafef7527542/go.mod h1:tv2ec8nA7vRpSYX7/MbP52ihrUMXIHit54CQMq8npXQ=
+github.com/dgraph-io/ristretto v0.0.4-0.20201207174236-c72a155bcf05 h1:oGrFgMCUMLUNfufaShfLY+DVpTC9crE+N3ZthjaA38A=
+github.com/dgraph-io/ristretto v0.0.4-0.20201207174236-c72a155bcf05/go.mod h1:tv2ec8nA7vRpSYX7/MbP52ihrUMXIHit54CQMq8npXQ=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dgrijalva/jwt-go/v4 v4.0.0-preview1 h1:CaO/zOnF8VvUfEbhRatPcwKVWamvbYd8tQGRWacE9kU=