Moving from fetchgit generated by go2nix to fetchFromGitHub where rev is

a tag

pkgs/servers/monitoring/prometheus/haproxy-exporter.nix

@@ -1,4 +1,4 @@
-{ stdenv, lib, buildGoPackage, fetchgit, fetchhg, fetchbzr, fetchsvn }:
+{ stdenv, lib, buildGoPackage, fetchFromGitHub }:
 
 buildGoPackage rec {
   name = "haproxy_exporter-${version}";
@@ -7,9 +7,10 @@ buildGoPackage rec {
 
   goPackagePath = "github.com/prometheus/haproxy_exporter";
 
-  src = fetchgit {
+  src = fetchFromGitHub {
     inherit rev;
-    url = "https://github.com/prometheus/haproxy_exporter";
+    owner = "prometheus";
+    repo = "haproxy_exporter";
     sha256 = "0cwls1d4hmzjkwc50mjkxjb4sa4q6yq581wlc5sg9mdvl6g91zxr";
   };