Building the site makes the Git working tree dirty

[Jayman2000]

After I build the site, my Git working tree is dirty. Here are some steps to reproduce:

1. Make sure that your Git working tree is clean. In other words, when you run git status, it should output something like this:

   $ git status
   On branch main
   Your branch is up to date with 'upstream/main'.
   
   nothing to commit, working tree clean

2. Follow the README’s instructions for building and previewing the site locally.

3. Once the Web page loads in your browser, close out of it.

4. In your terminal, press Ctrl+C to stop the yarn start command.

5. Run git status. On my system, git status will say this:

   $ git status
   On branch main
   Your branch is up to date with 'upstream/main'.
   
   Changes not staged for commit:
     (use "git add <file>..." to update what will be committed)
     (use "git restore <file>..." to discard changes in working directory)
           modified:   yarn.lock
   
   Untracked files:
     (use "git add <file>..." to include in what will be committed)
           .yarn/
           .yarnrc.yml
   
   no changes added to commit (use "git add" and/or "git commit -a")

I’m using version 4.2.2 of Yarn if that makes a difference.