rust: change minimum supported version everywhere applicable

This will help users and downstream packaging.

contrib/nix/flake.nix

@@ -53,7 +53,7 b''
       # but uses formatter features from nightly.
       # TODO: make cargo use the formatter from nightly automatically
       #       (not supported by rustup/cargo yet? workaround?)
-      # rustPlatform = pkgs.rust-bin.stable."1.61.0".default;
+      # rustPlatform = pkgs.rust-bin.stable."1.79.0".default;
       # rustPlatformFormatter = pkgs.rust-bin.nightly."2023-04-20".default;
 
       # The CI uses an old version of the Black code formatter,

rust/README.rst

@@ -83,7 +83,7 b' Minimum Supported Rust Version'
 ------------------------------
 
 The minimum supported rust version (MSRV) is specified in the `Clippy`_
-configuration file at ``rust/clippy.toml``. It is set to be ``1.61.0`` as of
+configuration file at ``rust/clippy.toml``. It is set to be ``1.79.0`` as of
 this writing, but keep in mind that the authoritative value is the one
 from the configuration file.
 

rust/clippy.toml

@@ -1,1 +1,1 b''
-msrv = "1.61.0"
+msrv = "1.79.0"