radicle-fetch: Replace manual std::matches!() impl

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

crates/radicle-fetch/src/state.rs

@@ -136,10 +136,7 @@ impl FetchResult {
     }
 
     pub fn is_success(&self) -> bool {
-        match self {
-            Self::Success { .. } => true,
-            Self::Failed { .. } => false,
-        }
+        std::matches!(self, Self::Success { .. })
     }
 }