KeyError: 'labels' during Distilling Zero Shot Classification

EDIT: I confirmed that this happens with the example script as it is, so no other changes are required to reproduce this. ## Environment info <!-- You can run the command `transformers-cli env` and copy-and-paste its output below. Don't forget to fill out the missing fields in that output! --> - `transformers` version: 4.6.1 - Platform: Linux-5.4.104+-x86_64-with-Ubuntu-18.04-bionic - Python version: 3.7.10 - PyTorch version (GPU?): 1.8.1+cu101 (True) - Tensorflow version (GPU?): 2.5.0 (True) - Using GPU in script?: Yes (NVIDIA P100) - Using distributed or parallel set-up in script?: No ### Who can help Tagging @VictorSanh @sgugger, @patil-suraj (please correct me if I'm wrong) <!-- Your issue will be replied to more quickly if you can figure out the right person to tag with @ If you know how to use git blame, that is the easiest way, otherwise, here is a rough guide of **who to tag**. Please tag fewer than 3 people. Models: - albert, bert, xlm: @LysandreJik - blenderbot, bart, marian, pegasus, encoderdecoder, t5: @patrickvonplaten, @patil-suraj - longformer, reformer, transfoxl, xlnet: @patrickvonplaten - fsmt: @stas00 - funnel: @sgugger - gpt2: @patrickvonplaten, @LysandreJik - rag: @patrickvonplaten, @lhoestq - tensorflow: @Rocketknight1 Library: - benchmarks: @patrickvonplaten - deepspeed: @stas00 - ray/raytune: @richardliaw, @amogkam - text generation: @patrickvonplaten - tokenizers: @LysandreJik - trainer: @sgugger - pipelines: @LysandreJik Documentation: @sgugger Model hub: - for issues with a model report at https://discuss.huggingface.co/ and tag the model's creator. HF projects: - datasets: [different repo](https://github.com/huggingface/datasets) - rust tokenizers: [different repo](https://github.com/huggingface/tokenizers) Examples: - maintained examples (not research project or legacy): @sgugger, @patil-suraj - research_projects/bert-loses-patience: @JetRunner - research_projects/distillation: @VictorSanh --> ## Information Model I am using (Be…