Bump MSRV to 1.57.0 to more correctly match the codebase. (#1760)

* Bump MSRV to 1.57.0 to more correctly match used methods.

* Update Cargo.toml

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Co-authored-by: Geoffroy Couprie <geo.couprie@gmail.com>

Cargo.toml

@@ -14,7 +14,7 @@ edition = "2021"
 autoexamples = false
 
 # also update in README.md (badge and "Rust version requirements" section)
-rust-version = "1.56"
+rust-version = "1.65.0"
 
 include = [
   "CHANGELOG.md",