chore(deps): bump flutter_markdown from 0.6.23 to 0.7.1

Bumps [flutter_markdown](https://github.com/flutter/packages/tree/main/packages) from 0.6.23 to 0.7.1.
- [Release notes](https://github.com/flutter/packages/releases)
- [Commits](https://github.com/flutter/packages/commits/flutter_markdown-v0.7.1/packages)

---
updated-dependencies:
- dependency-name: flutter_markdown
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pubspec.yaml

@@ -10,7 +10,7 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  flutter_markdown: ^0.6.18+3
+  flutter_markdown: ">=0.6.18+3 <0.8.0"
   flutter_math_fork: ^0.7.2
   markdown: ^7.1.1