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/rust-toolchain b/rust-toolchain
index 32b7211..91951fd 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-1.40.0
+1.61.0