fix: update font configuration

modules/fonts/default.nix

@@ -1,5 +1,16 @@
+{ pkgs, ... }:
+
 {
   imports = [
     ./iosevka.nix
   ];
+
+  fonts = {
+    # disable default font packages (see https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/config/fonts/packages.nix)
+    enableDefaultPackages = false;
+    packages = with pkgs; [
+      dejavu_fonts
+      liberation_ttf
+    ];
+  };
 }

modules/fonts/iosevka.nix

@@ -1,7 +1,14 @@
 { pkgs, ... }:
 
 {
-  fonts.packages = with pkgs; [
-    (iosevka-bin.override { variant = "SGr-IosevkaTermSS08"; })
-  ];
+  fonts = {
+    packages = with pkgs; [
+      (iosevka-bin.override { variant = "SGr-IosevkaTermSS08"; })
+    ];
+    fontconfig = {
+      defaultFonts = {
+        monospace = [ "Iosevka Term SS08" ];
+      };
+    };
+  };
 }