Chore: Upgrade grafana-plugin-sdk-go to v0.137.0 (#50443)

Co-authored-by: Todd Treece <todd.treece@grafana.com>

go.mod

@@ -53,7 +53,7 @@ require (
 	github.com/grafana/cuetsy v0.0.3
 	github.com/grafana/grafana-aws-sdk v0.10.3
 	github.com/grafana/grafana-azure-sdk-go v1.2.0
-	github.com/grafana/grafana-plugin-sdk-go v0.136.0
+	github.com/grafana/grafana-plugin-sdk-go v0.137.0
 	github.com/grafana/loki v1.6.2-0.20211015002020-7832783b1caa
 	github.com/grpc-ecosystem/go-grpc-middleware v1.3.0
 	github.com/hashicorp/go-hclog v1.0.0
@@ -64,7 +64,6 @@ require (
 	github.com/jmespath/go-jmespath v0.4.0
 	github.com/json-iterator/go v1.1.12
 	github.com/jung-kurt/gofpdf v1.16.2
-	github.com/laher/mergefs v0.1.1
 	github.com/lib/pq v1.10.4
 	github.com/linkedin/goavro/v2 v2.10.0
 	github.com/m3db/prometheus_remote_client_golang v0.4.4