make-snapshot: Fix Psych::DisallowedClass with newer psych

```
$ tool/format-release ../www.ruby-lang.org 4.0.0-preview2 .
/opt/rubies/3.4.6/lib/ruby/3.4.0/psych/class_loader.rb:99:in 'Psych::ClassLoader::Restricted#find': Tried to load unspecified class: Date (Psych::DisallowedClass)
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/class_loader.rb:28:in 'Psych::ClassLoader#load'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/class_loader.rb:40:in 'Psych::ClassLoader#date'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/scalar_scanner.rb:65:in 'Psych::ScalarScanner#tokenize'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:65:in 'Psych::Visitors::ToRuby#deserialize'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:129:in 'Psych::Visitors::ToRuby#visit_Psych_Nodes_Scalar'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:30:in 'Psych::Visitors::Visitor#visit'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:6:in 'Psych::Visitors::Visitor#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:35:in 'Psych::Visitors::ToRuby#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:346:in 'block in Psych::Visitors::ToRuby#revive_hash'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:344:in 'Array#each'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:344:in 'Enumerable#each_slice'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:344:in 'Psych::Visitors::ToRuby#revive_hash'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:168:in 'Psych::Visitors::ToRuby#visit_Psych_Nodes_Mapping'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:30:in 'Psych::Visitors::Visitor#visit'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:6:in 'Psych::Visitors::Visitor#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:35:in 'Psych::Visitors::ToRuby#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:339:in 'block in Psych::Visitors::ToRuby#register_empty'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:339:in 'Array#each'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:339:in 'Psych::Visitors::ToRuby#register_empty'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:147:in 'Psych::Visitors::ToRuby#visit_Psych_Nodes_Sequence'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:30:in 'Psych::Visitors::Visitor#visit'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:6:in 'Psych::Visitors::Visitor#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:35:in 'Psych::Visitors::ToRuby#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:319:in 'Psych::Visitors::ToRuby#visit_Psych_Nodes_Document'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:30:in 'Psych::Visitors::Visitor#visit'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/visitor.rb:6:in 'Psych::Visitors::Visitor#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych/visitors/to_ruby.rb:35:in 'Psych::Visitors::ToRuby#accept'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych.rb:336:in 'Psych.safe_load'
        from /opt/rubies/3.4.6/lib/ruby/3.4.0/psych.rb:371:in 'Psych.load'
        from tool/format-release:80:in 'Tarball.parse'
        from tool/format-release:269:in 'Object#main'
        from tool/format-release:272:in '<main>'
```

1 files changed, 1 insertions, 1 deletions

diff --git a/tool/format-release b/tool/format-release
index b38263f9f4..0505df700b 100755
--- a/tool/format-release
+++ b/tool/format-release
@@ -77,7 +77,7 @@ eom
     end
 
     uri = "https://cache.ruby-lang.org/pub/tmp/ruby-info-#{version}-draft.yml"
-    info = YAML.load(URI(uri).read)
+    info = YAML.unsafe_load(URI(uri).read)
     if info.size != 1
       raise "unexpected info.yml '#{uri}'"
     end