Add Gemma 3 1b IT toe Gemma examples (#2809)

- Updates the Gemma example to include Gemma 3 1b instruction tuned.

candle-examples/examples/gemma/main.rs

@@ -50,6 +50,8 @@ enum Which {
     InstructV2_9B,
     #[value(name = "3-1b")]
     BaseV3_1B,
+    #[value(name = "3-1b-it")]
+    InstructV3_1B,
 }
 
 enum Model {
@@ -272,6 +274,7 @@ fn main() -> Result<()> {
             Which::BaseV2_9B => "google/gemma-2-9b".to_string(),
             Which::InstructV2_9B => "google/gemma-2-9b-it".to_string(),
             Which::BaseV3_1B => "google/gemma-3-1b-pt".to_string(),
+            Which::InstructV3_1B => "google/gemma-3-1b-it".to_string(),
         },
     };
     let repo = api.repo(Repo::with_revision(
@@ -292,13 +295,10 @@ fn main() -> Result<()> {
             .split(',')
             .map(std::path::PathBuf::from)
             .collect::<Vec<_>>(),
-        None => {
-            if args.which == Which::BaseV3_1B {
-                vec![repo.get("model.safetensors")?]
-            } else {
-                candle_examples::hub_load_safetensors(&repo, "model.safetensors.index.json")?
-            }
-        }
+        None => match args.which {
+            Which::BaseV3_1B | Which::InstructV3_1B => vec![repo.get("model.safetensors")?],
+            _ => candle_examples::hub_load_safetensors(&repo, "model.safetensors.index.json")?,
+        },
     };
     println!("retrieved the files in {:?}", start.elapsed());
     let tokenizer = Tokenizer::from_file(tokenizer_filename).map_err(E::msg)?;
@@ -331,7 +331,7 @@ fn main() -> Result<()> {
             let model = Model2::new(args.use_flash_attn, &config, vb)?;
             Model::V2(model)
         }
-        Which::BaseV3_1B => {
+        Which::BaseV3_1B | Which::InstructV3_1B => {
             let config: Config3 = serde_json::from_reader(std::fs::File::open(config_filename)?)?;
             let model = Model3::new(args.use_flash_attn, &config, vb)?;
             Model::V3(model)