Switch minima theme source to donglua/minima

This change updates the Gemfile to source the `minima` theme directly from the `donglua/minima` GitHub repository, as requested.

Note: You will need to run `bundle install` locally to update your `Gemfile.lock`.

Author: google-labs-jules[bot]

Gemfile

@@ -10,7 +10,7 @@ source "https://rubygems.org"
 gem "jekyll", "~> 4.4.1"
 gem "logger"  # Ruby 4.0 需要显式添加
 # This is the default theme for new Jekyll sites. You may change this to anything you like.
-gem "minima", "~> 2.5"
+gem "minima", git: "https://github.com/donglua/minima"
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
 # gem "github-pages", group: :jekyll_plugins