Revert MSRV (#421)

Author: lwshang

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  rust-version: 1.71.1
+  rust-version: 1.65.0
 
 jobs:
   build:

.github/workflows/examples.yml

@@ -11,7 +11,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  rust-version: 1.71.1
+  rust-version: 1.65.0
   dfx-version: 0.14.1
   wasmtime-version: 10.0.1
 

Cargo.toml

@@ -14,7 +14,12 @@ members = [
 authors = ["DFINITY Stiftung <[email protected]>"]
 edition = "2021"
 repository = "https://github.com/dfinity/cdk-rs"
-rust-version = "1.71.1"
+# MSRV
+# Avoid updating this field unless we use new Rust features
+# Sync rust-version in following CI files:
+# .github/workflows/ci.yml
+# .github/workflows/examples.yml
+rust-version = "1.65.0"
 license = "Apache-2.0"
 
 [profile.canister-release]

rust-toolchain.toml

@@ -3,7 +3,5 @@ channel = "1.71.1"
 targets = ["wasm32-unknown-unknown"]
 components = ["rustfmt", "clippy"]
 
-# Sync rust-version in following files
-# Cargo.toml
-# .github/workflows/ci.yml
-# .github/workflows/examples.yml
+# The version only influences the local develop environment.
+# No need to sync with Cargo.toml and CI.