fix: remove meta_name from DigestMetaPlugin default implementation

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/meta_plugin/digest.rs

@@ -72,7 +72,6 @@ impl Default for DigestMetaPlugin {
         Self {
             hasher: None,
             is_finalized: false,
-            meta_name: "digest".to_string(),
             outputs: std::collections::HashMap::new(),
             options: std::collections::HashMap::new(),
         }