gentium-plus: rename from gentium

Upstream has named this font 'GentiumPlus' all the time, and stopped
releasing new versions of this font, but began to release a font named
simply 'Gentium' straight at version 7.000.

nixos/tests/fontconfig-default-fonts.nix

···
         cantarell-fonts
         twitter-color-emoji
         source-code-pro
-        gentium
+        gentium-plus
       ];
       fonts.fontconfig.defaultFonts = {
         serif = [ "Gentium Plus" ];

pkgs/by-name/ge/gentium/package.nix pkgs/by-name/ge/gentium-plus/package.nix

···
 }:
 
 stdenvNoCC.mkDerivation (finalAttrs: {
-  pname = "gentium";
+  pname = "gentium-plus";
   version = "6.200";
 
   src = fetchzip {

pkgs/by-name/ho/hottext/package.nix

···
   lib,
   buildNimPackage,
   fetchFromSourcehut,
-  gentium,
+  gentium-plus,
   makeDesktopItem,
 }:
 
···
 
   lockFile = ./lock.json;
 
-  HOTTEXT_FONT_PATH = "${gentium}/share/fonts/truetype/GentiumPlus-Regular.ttf";
+  HOTTEXT_FONT_PATH = "${gentium-plus}/share/fonts/truetype/GentiumPlus-Regular.ttf";
 
   desktopItem = makeDesktopItem {
     categories = [ "Utility" ];

pkgs/by-name/si/sile/package.nix

···
   libiconv,
   # FONTCONFIG_FILE
   makeFontsConf,
-  gentium,
+  gentium-plus,
 
   # passthru.tests
   runCommand,
···
 
   FONTCONFIG_FILE = makeFontsConf {
     fontDirectories = [
-      gentium
+      gentium-plus
     ];
   };
   strictDeps = true;