THRIFT-5600: upgrade rust toolchain to 1.61 and edition 2021
THRIFT-5606: Wrong indent for const double
Client: rs
Patch: Ommy Zhang <tdxdxoz@gmail.com>

This closes #2634
diff --git a/lib/rs/src/protocol/compact.rs b/lib/rs/src/protocol/compact.rs
index 566f344..87cfbfc 100644
--- a/lib/rs/src/protocol/compact.rs
+++ b/lib/rs/src/protocol/compact.rs
@@ -84,14 +84,13 @@
         let header = self.read_byte()?;
         let element_type = collection_u8_to_type(header & 0x0F)?;
 
-        let element_count;
         let possible_element_count = (header & 0xF0) >> 4;
-        if possible_element_count != 15 {
+        let element_count = if possible_element_count != 15 {
             // high bits set high if count and type encoded separately
-            element_count = possible_element_count as i32;
+            possible_element_count as i32
         } else {
-            element_count = self.transport.read_varint::<u32>()? as i32;
-        }
+            self.transport.read_varint::<u32>()? as i32
+        };
 
         Ok((element_type, element_count))
     }