Fix non-exhaustive pattern match in rsky-firehose binary

Add missing Ok(None) arm to the match on firehose::read() in process().
The function returns Ok(None) for intentionally skipped message types
(#info, #sync, unknown types) and for recoverable decode errors that the
library already logs. The Err arm is preserved to catch genuine CBOR
header parse failures.

Fixes #150

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jmcauley

rsky-firehose/src/main.rs

@@ -268,6 +268,7 @@ async fn process(message: Vec<u8>, client: &reqwest::Client) {
                 };
             }
         }
+        Ok(None) => (),
         Err(error) => eprintln!(
             "@LOG: Error unwrapping message and header: {}",
             error.to_string()