chore: upgrade iavl to v0.17.3-osmo-v4 - fix old height export (#131)

* iavl v0.17.3-osmo-v4.rc2

* upgrade iavl to v0.17.3-osmo-v4

go.mod

@@ -69,4 +69,4 @@ replace github.com/gin-gonic/gin => github.com/gin-gonic/gin v1.7.0
 
 replace github.com/tendermint/tm-db => github.com/osmosis-labs/tm-db v0.6.5-0.20210911033928-ba9154613417
 
-replace github.com/cosmos/iavl => github.com/osmosis-labs/iavl v0.17.3-osmo-v3
+replace github.com/cosmos/iavl => github.com/osmosis-labs/iavl v0.17.3-osmo-v4

go.sum

@@ -617,6 +617,10 @@ github.com/ory/dockertest v3.3.5+incompatible h1:iLLK6SQwIhcbrG783Dghaaa3WPzGc+4
 github.com/ory/dockertest v3.3.5+incompatible/go.mod h1:1vX4m9wsvi00u5bseYwXaSnhNrne+V0E6LAcBILJdPs=
 github.com/osmosis-labs/iavl v0.17.3-osmo-v3 h1:q2Qv3+DK52w5b68I96VApHI05jBu7HeQK/YDttKh/jY=
 github.com/osmosis-labs/iavl v0.17.3-osmo-v3/go.mod h1:lJEOIlsd3sVO0JDyXWIXa9/Ur5FBscP26zJx0KxHjto=
+github.com/osmosis-labs/iavl v0.17.3-osmo-v4 h1:U1HA2WEMAYVPjeJlfClH10ajv6O0C1C1jk/SQxDPwyM=
+github.com/osmosis-labs/iavl v0.17.3-osmo-v4/go.mod h1:lJEOIlsd3sVO0JDyXWIXa9/Ur5FBscP26zJx0KxHjto=
+github.com/osmosis-labs/iavl v0.17.3-osmo-v4.rc2 h1:Sq5909z6y/tfN4lrOrqgSwZWjqQzmyeTtVfIlRK9tz0=
+github.com/osmosis-labs/iavl v0.17.3-osmo-v4.rc2/go.mod h1:lJEOIlsd3sVO0JDyXWIXa9/Ur5FBscP26zJx0KxHjto=
 github.com/osmosis-labs/tm-db v0.6.5-0.20210911033928-ba9154613417 h1:otchJDd2SjFWfs7Tse3ULblGcVWqMJ50BE02XCaqXOo=
 github.com/osmosis-labs/tm-db v0.6.5-0.20210911033928-ba9154613417/go.mod h1:dptYhIpJ2M5kUuenLr+Yyf3zQOv1SgBZcl8/BmWlMBw=
 github.com/otiai10/copy v1.6.0 h1:IinKAryFFuPONZ7cm6T6E2QX/vcJwSnlaA5lfoaXIiQ=