Add ICU and python build deps for mise runtimes

dotnet needs libicu for globalization support. python-build needs
zlib, readline, bzip2, xz, libffi, ncurses, and sqlite.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nixos/ringtail/configuration.nix

@@ -134,6 +134,14 @@
     pkg-config
     openssl
     gnupg
+    icu
+    zlib
+    readline
+    bzip2
+    xz
+    libffi
+    ncurses
+    sqlite
   ];
 
   # Allow running dynamically linked binaries (mise-installed runtimes, etc.)