Update CO2 metric from kg to g

HuggingFace requires co2 emissions be displayed in gram instead of kilograms.
CodeCarbon delivers them in KG, hence this commit
- https://huggingface.co/docs/hub/en/model-cards-co2

README.md

@@ -31,7 +31,7 @@ inference:
     length_penalty: 0.3
     early_stopping: true
 co2_eq_emissions:
-  emissions: 0.25
+  emissions: 250
   source: CodeCarbon
   training_type: fine-tuning
   geographical_location: United States of America