mrtg: 2.17.4 -> 2.17.7

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools. This update was made based on information from https://repology.org/metapackage/mrtg/versions.

pkgs/tools/misc/mrtg/default.nix

···
 
 stdenv.mkDerivation rec {
 
-  version = "2.17.4";
+  version = "2.17.7";
   name = "mrtg-${version}";
 
   src = fetchurl {
     url = "https://oss.oetiker.ch/mrtg/pub/${name}.tar.gz";
-    sha256 = "0r93ipscfp7py0b1dcx65s58q7dlwndqhprf8w4945a0h2p7zyjy";
+    sha256 = "1hrjqfi290i936nblwpfzjn6v8d8p69frcrvml206nxiiwkcp54v";
   };
 
   buildInputs = [