Ignore local environment .tool-versions configuration file

The `.tool-versions` file configures one's local environment and should
likely not be committed. Its format is defined by
[asdf-vm](https://asdf-vm.com), and is similar to
[nvm](https://github.com/nvm-sh/nvm), [rvm](https://rvm.io), or
[rbenv](https://github.com/rbenv/rbenv). Ignore this file will help
ensure the configuration is not accidentally committed to the
repository.

.gitignore

@@ -47,6 +47,7 @@ bundle/ios/assets/gutenberg/packages/block-library/src/*
 
 # Local configuration file (sdk path, etc)
 local.properties
+.tool-versions
 
 # XCode
 build/