github actions: update recommended lowest supported Rust to 1.77

Signed-off-by: Chung Chung <cchung@redhat.com>

Author: C2Redhat

Cargo.toml

@@ -3,7 +3,7 @@ name = "loopdev-3"
 description = "Setup and control loop devices"
 version = "0.5.1"
 authors = ["Stratis Developers <stratis-devel@lists.fedorahosted.org>", "Michael Daffin <michael@daffin.io>"]
-rust-version = "1.74.0"
+rust-version = "1.77.0"  # LOWEST SUPPORTED RUST TOOLCHAIN
 license = "MIT"
 documentation = "https://docs.rs/loopdev-3"
 repository = "https://github.com/stratis-storage/loopdev-3"