svgbob: fix build

See https://hydra.nixos.org/build/102480738

Bumping to latest version (which is 0.4.2 according to Cargo.lock) fixes
the build error. As no dependency changes happened, cargoSha256 doesn't
need to be updated.

ZHF #68361

pkgs/tools/graphics/svgbob/default.nix

@@ -2,13 +2,13 @@
 
 rustPlatform.buildRustPackage rec {
   pname = "svgbob";
-  version = "unstable-2018-10-05";
+  version = "0.4.2";
 
   src = fetchFromGitHub {
     owner = "ivanceras";
     repo = pname;
-    rev = "43fb0364e989d0e9a7656b148c947d47cc769622";
-    sha256 = "1imjj57dx1af3wrs214yzaa2qfk8ld00nj3nx4z450gw2xjjj1gw";
+    rev = "0febc4377134a2ea3b3cd43ebdf5ea688a0e7432";
+    sha256 = "1n0w5b3fjgbczy1iw52172x1p3y1bvw1qpz77fkaxkhrkgfd7vwr";
   };
 
   sourceRoot = "source/svgbob_cli";