Bump rust toolchain to 1.64

Author: DavidSouther

.github/workflows/rust.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: 1.63
+          toolchain: 1.64
           override: true
           components: clippy, rustfmt
       - uses: actions-rs/cargo@v1

rust_dev_preview/rust-toolchain.toml

@@ -1,3 +1,3 @@
 # This should be kept in sync with https://github.com/awslabs/aws-sdk-rust#supported-rust-versions-msrv
 [toolchain]
-channel = "1.63"
+channel = "1.64"