text: Title: Improve `dev/build.py`
  Body: ### Summary
  
  We only need to restore the files modified by this script:
  
  ```diff
  diff --git a/dev/build.py b/dev/build.py
  index 2133aebcb..7cbb51273 100644
  --- a/dev/build.py
  +++ b/dev/build.py
  @@ -26,7 +26,14 @@ def restore_changes():
       try:
           yield
       finally:
  -        subprocess.check_call(["git", "restore", ":^dev/build.py"])
  +        subprocess.check_call(
  +            [
  +                "git",
  +                "restore",
  +                "README.md",
  +                "pyproject.toml",
  +            ]
  +        )
  ```
  
  ### Notes
  
  - Make sure to open a PR from a **non-master** branch.
  - Sign off the commit using the `-s` flag when making a commit:
  
    ```sh
    git commit -s -m "..."
             # ^^ make sure to use this
    ```
  
  - Include `#{issue_number}` (e.g. `#123`) in the PR description when opening a PR.
  