build(deps): bump github.com/tendermint/tm-db from 0.1.1 to 0.2.0 (#4001)

Bumps [github.com/tendermint/tm-db](https://github.com/tendermint/tm-db) from 0.1.1 to 0.2.0.
- [Release notes](https://github.com/tendermint/tm-db/releases)
- [Changelog](https://github.com/tendermint/tm-db/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tendermint/tm-db/compare/v0.1.1...v0.2.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

go.mod

@@ -26,7 +26,7 @@ require (
 	github.com/spf13/viper v1.4.0
 	github.com/stretchr/testify v1.4.0
 	github.com/tendermint/go-amino v0.14.1
-	github.com/tendermint/tm-db v0.1.1
+	github.com/tendermint/tm-db v0.2.0
 	golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2
 	golang.org/x/net v0.0.0-20190628185345-da137c7871d7
 	google.golang.org/grpc v1.23.1

go.sum

@@ -180,6 +180,8 @@ github.com/tendermint/go-amino v0.14.1 h1:o2WudxNfdLNBwMyl2dqOJxiro5rfrEaU0Ugs6o
 github.com/tendermint/go-amino v0.14.1/go.mod h1:i/UKE5Uocn+argJJBb12qTZsCDBcAYMbR92AaJVmKso=
 github.com/tendermint/tm-db v0.1.1 h1:G3Xezy3sOk9+ekhjZ/kjArYIs1SmwV+1OUgNkj7RgV0=
 github.com/tendermint/tm-db v0.1.1/go.mod h1:0cPKWu2Mou3IlxecH+MEUSYc1Ch537alLe6CpFrKzgw=
+github.com/tendermint/tm-db v0.2.0 h1:rJxgdqn6fIiVJZy4zLpY1qVlyD0TU6vhkT4kEf71TQQ=
+github.com/tendermint/tm-db v0.2.0/go.mod h1:0cPKWu2Mou3IlxecH+MEUSYc1Ch537alLe6CpFrKzgw=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=