Add --config as a command-line option (#422)

src/cli.rs

@@ -17,6 +17,9 @@ use crate::RawSettings;
 pub struct Cli {
     #[arg(required = true)]
     pub files: Vec<PathBuf>,
+    /// Path to the `pyproject.toml` file to use for configuration.
+    #[arg(long)]
+    pub config: Option<PathBuf>,
     /// Enable verbose logging.
     #[arg(short, long)]
     pub verbose: bool,

src/main.rs

@@ -216,7 +216,9 @@ fn inner_main() -> Result<ExitCode> {
         Some(path) => debug!("Found project root at: {:?}", path),
         None => debug!("Unable to identify project root; assuming current directory..."),
     };
-    let pyproject = pyproject::find_pyproject_toml(&project_root);
+    let pyproject = cli
+        .config
+        .or_else(|| pyproject::find_pyproject_toml(&project_root));
     match &pyproject {
         Some(path) => debug!("Found pyproject.toml at: {:?}", path),
         None => debug!("Unable to find pyproject.toml; using default settings..."),