gh-40642: bump nauty to version 2.9.0
    
Nauty 2.9.0 has been released on July 17, 2025.
- web page https://pallini.di.uniroma1.it
- changes https://pallini.di.uniroma1.it/changes24-29.txt
- The tar.gz file can be found at
https://pallini.di.uniroma1.it/nauty2_9_0.tar.gz

For macOS users, this is the current homebrew version.

### 📝 Checklist

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- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

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URL: #40642
Reported by: David Coudert
Reviewer(s): Frédéric Chapoton

Author: Release Manager

build/pkgs/nauty/checksums.ini

@@ -1,4 +1,4 @@
 tarball=nauty${VERSION}.tar.gz
-sha1=23504eeae95a1a8a9abfd47029b4ff9da886471f
-sha256=c97ab42bf48796a86a598bce3e9269047ca2b32c14fc23e07208a244fe52c4ee
+sha1=ec693d4f56b08934d061c825ddad2c83a9dcda91
+sha256=7b38834c7cefe17d25e05eef1ef3882fa9cd1933f582b9eb9de7477411956053
 upstream_url=https://pallini.di.uniroma1.it/nauty${VERSION_MAJOR}_${VERSION_MINOR}_${VERSION_MICRO}.tar.gz

build/pkgs/nauty/package-version.txt

@@ -1 +1 @@
-2.8.9
+2.9.0