PMM-4712 add pprof (#151)

Co-authored-by: Roman Novikov <[email protected]>

Author: ylacancellera

cmd/postgres_exporter/main.go

@@ -18,6 +18,8 @@ import (
 	"net/http"
 	"os"
 
+	_ "net/http/pprof"
+
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/prometheus-community/postgres_exporter/collector"