Run precommit in its own job, cache the data (#3094)

.circleci/config.yml

             pytest --cov=ml-agents --cov=ml-agents-envs --cov=gym-unity --cov-report html --junitxml=test-reports/junit.xml -p no:warnings
 
       - run:
-          name: Check Code Style using pre-commit
-          command: |
-            . venv/bin/activate
-            pre-commit run --show-diff-on-failure --all-files
-
-      - run:
           name: Verify there are no hidden/missing metafiles.
           # Renaming files or deleting files can leave metafiles behind that makes Unity very unhappy.
           command: |
           path: htmlcov
           destination: htmlcov
 
+  pre-commit:
+    docker:
+      - image: circleci/python:3.7.3
+    working_directory: ~/repo/
+
+    steps:
+      - checkout
+      - run:
+          name: Combine precommit config and python versions for caching
+          command: |
+            cat .pre-commit-config.yaml > pre-commit-deps.txt
+            python -VV >> pre-commit-deps.txt
+
+      - restore_cache:
+          keys:
+          - v1-precommit-deps-{{ checksum "pre-commit-deps.txt" }}
+
+      - run:
+          name: Install Dependencies
+          command: |
+            python3 -m venv venv
+            . venv/bin/activate
+            pip install --upgrade pip
+            pip install --upgrade setuptools
+            pip install pre-commit
+            # Install the hooks now so that they'll be cached
+            pre-commit install-hooks
+
+      - save_cache:
+          paths:
+            - ~/.cache/pre-commit
+            - ./venv
+          key: v1-precommit-deps-{{ checksum "pre-commit-deps.txt" }}
+
+      - run:
+          name: Check Code Style using pre-commit
+          command: |
+            . venv/bin/activate
+            pre-commit run --show-diff-on-failure --all-files
 
   markdown_link_check:
     parameters:
           pip_constraints: test_constraints_max_tf2_version.txt
       - markdown_link_check
       - protobuf_generation_check
+      - pre-commit
       - deploy:
           name: deploy ml-agents-envs
           directory: ml-agents-envs

.pre-commit-config.yaml

         types: [markdown]
     -   id: check-merge-conflict
         args: [--assume-in-merge]
+    -   id: check-yaml
+        # Won't handle the templating in yamato
+        exclude: \.yamato/*
-
-
 
 -   repo: https://github.com/pre-commit/mirrors-pylint
     rev: v2.4.4

config/offline_bc_config.yaml

     num_layers: 2
     sequence_length: 32
     memory_size: 256
-    demo_path: ./UnitySDK/Assets/Demonstrations/<Your_Demo_File>.demo
+    # Change the path here to point to your demo files
+    demo_path: ./UnitySDK/Assets/Demonstrations/Your_Demo_File.demo
 
 FoodCollector:
     trainer: offline_bc
     batches_per_epoch: 5
     num_layers: 2
     hidden_units: 128
-    sequence_length: 16
     use_recurrent: true
     memory_size: 256
     sequence_length: 32

config/sac_trainer_config.yaml

     summary_freq: 3000
 
 Hallway:
-    use_recurrent: true
     sequence_length: 32
     num_layers: 2
     hidden_units: 128
     use_recurrent: true
 
 VisualHallway:
-    use_recurrent: true
     sequence_length: 32
     num_layers: 1
     hidden_units: 128

test_requirements.txt

 # Test-only dependencies should go here, not in setup.py
 pytest>=3.2.2,<4.0.0
-pre-commit
 pytest-cov==2.6.1