Bump google_fonts in /experimental/varfont_shader_puzzle (#1600)

Bumps [google_fonts](https://github.com/material-foundation/google-fonts-flutter) from 3.0.1 to 4.0.0.
- [Release notes](https://github.com/material-foundation/google-fonts-flutter/releases)
- [Changelog](https://github.com/material-foundation/google-fonts-flutter/blob/main/CHANGELOG.md)
- [Commits](https://github.com/material-foundation/google-fonts-flutter/compare/v3.0.1...v4.0.0)

---
updated-dependencies:
- dependency-name: google_fonts
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

experimental/varfont_shader_puzzle/pubspec.yaml

@@ -37,7 +37,7 @@ dependencies:
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.2
-  google_fonts: ^3.0.1
+  google_fonts: ^4.0.0
 
 dev_dependencies:
   flutter_test: