bump pd version to v2.0.5

[tiancaiamao]

What problem does this PR solve?

I'm dealing with pingcap/tidb#7922, and find that after tidb-tools introduce Go module, TiDB will meet this error:

CGO_ENABLED=0 GO111MODULE=on go build   -ldflags '-X "github.com/pingcap/parser/mysql.TiDBReleaseVersion=v2.1.0-rc.3-134-gcf432188b-dirty" -X "github.com/pingcap/tidb/util/printer.TiDBBuildTS=2018-10-31 03:31:00" -X "github.com/pingcap/tidb/util/printer.TiDBGitHash=cf432188beaa2213e62ac7ad8613a1314f8e6da7" -X "github.com/pingcap/tidb/util/printer.TiDBGitBranch=go-module" -X "github.com/pingcap/tidb/util/printer.GoVersion=go version go1.11.1 linux/amd64" ' -o bin/tidb-server tidb-server/main.go
go: finding github.com/pingcap/pd/client latest
tidb-server/main.go:29:2: unknown import path "github.com/pingcap/pd/client": cannot find module providing package github.com/pingcap/pd/client

The pd version is too old, I guess TiDB can't find a compatible version.

What is changed and how it works?

Try to update its pd version

Check List

Tests

• No code

[WangXiangUSTC]

LGTM

[july2993]

LGTM