Specify minimum Rust version

Author: huangsam

Cargo.toml

@@ -6,6 +6,7 @@ resolver = "3"
 authors = ["Samuel Huang <[email protected]>"]
 version = "0.9.4"
 edition = "2024"
+rust-version = "1.85"
 readme = "README.md"
 repository = "https://github.com/huangsam/rustoku"
 license = "MIT"

rustoku-cli/Cargo.toml

@@ -4,6 +4,7 @@ description = "Command-line interface for the Rustoku library"
 authors.workspace = true
 version.workspace = true
 edition.workspace = true
+rust-version.workspace = true
 readme.workspace = true
 repository.workspace = true
 license.workspace = true

rustoku-lib/Cargo.toml

@@ -4,6 +4,7 @@ description = "Lightning-fast Sudoku solving and generation"
 authors.workspace = true
 version.workspace = true
 edition.workspace = true
+rust-version.workspace = true
 readme.workspace = true
 repository.workspace = true
 license.workspace = true