Fix R_HOME joining

crates/harp/src/command.rs

@@ -27,7 +27,7 @@ where
     // If `R_HOME` is defined use that
     let locations = COMMAND_R_LOCATIONS.map(|loc| {
         if let Ok(r_home) = std::env::var("R_HOME") {
-            std::path::Path::new(&r_home).join(loc)
+            std::path::Path::new(&r_home).join("bin").join(loc)
         } else {
             std::path::Path::new(loc).to_path_buf()
         }