go.mod: switch tidb-tools to release-3.1 to avoid pd/v4 deps

go.mod

@@ -12,7 +12,6 @@ require (
 	github.com/gogo/protobuf v1.3.1
 	github.com/google/btree v1.0.0
 	github.com/google/uuid v1.1.1
-	github.com/klauspost/cpuid v1.2.0 // indirect
 	github.com/montanaflynn/stats v0.5.0 // indirect
 	github.com/pingcap/check v0.0.0-20200212061837-5e12011dc712
 	github.com/pingcap/errors v0.11.5-0.20190809092503-95897b64e011
@@ -21,12 +20,11 @@ require (
 	github.com/pingcap/log v0.0.0-20200117041106-d28c14d3b1cd
 	github.com/pingcap/parser v3.1.0-beta.2.0.20200425032215-994651e9b6df+incompatible
 	github.com/pingcap/pd/v3 v3.1.1-0.20200426091027-e639f0b1e62b
-	github.com/pingcap/pd/v4 v4.0.2 // indirect
 	github.com/pingcap/tidb v1.1.0-beta.0.20200426082429-52b31342cb0e
-	github.com/pingcap/tidb-tools v4.0.0-rc.2.0.20200521050818-6dd445d83fe0+incompatible
+	github.com/pingcap/tidb-tools v4.0.0-beta.2.0.20200709092834-22f96ccb95f7+incompatible
 	github.com/pingcap/tipb v0.0.0-20200426072603-ce17d2d03251
-	github.com/prometheus/client_golang v1.0.0
-	github.com/prometheus/common v0.4.1
+	github.com/prometheus/client_golang v1.2.1
+	github.com/prometheus/common v0.7.0
 	github.com/sirupsen/logrus v1.4.2
 	github.com/spf13/cobra v0.0.5
 	github.com/spf13/pflag v1.0.5