[Fix] text-classification PL example (#6027)

Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

examples/text-classification/run_pl.sh

@@ -23,7 +23,7 @@ mkdir -p $OUTPUT_DIR
 # Add parent directory to python path to access lightning_base.py
 export PYTHONPATH="../":"${PYTHONPATH}"
 
-python3 run_pl_glue.py --data_dir $DATA_DIR \
+python3 run_pl_glue.py --gpus 1 --data_dir $DATA_DIR \
 --task $TASK \
 --model_name_or_path $BERT_MODEL \
 --output_dir $OUTPUT_DIR \