Set default mode to record-only

[awilkes]

Record-only enables most features. We don't want users to subset by default. They will enable it later.

awilkes@MacBook-Pro-2 pytest-launchable % python3 -m launchable_config --create                                        
Launchable configuration file is written to /Users/awilkes/code/launchable/pytest-launchable/.launchable.d/config.yml
awilkes@MacBook-Pro-2 pytest-launchable % cat /Users/awilkes/code/launchable/pytest-launchable/.launchable.d/config.yml
# Launchable test session configuration file
# See https://docs.launchableinc.com/resources/cli-reference for detailed usage of these options
#  
schema-version: 1.0
build-name: commit_hash
record-build:
  # Put your git repository location here
  source: .
  max_days: 30
record-session:
subset:
  # mode is subset, subset-and-rest, or record-only
  mode: record-only
  # if mode is subset or subset-and-rest, you must specify one of target/confidence/time
  # examples:
  #   target: 30%  # Create a variable time-based subset of the given percentage. (0%-100%)
  #   confidence: 30%  # Create a confidence-based subset of the given percentage. (0%-100%)
  #   time: 30m  # Create a fixed time-based subset. Select the best set of tests that run within the given time bound. (e.g. 10m for 10 minutes, 2h30m for 2.5 hours, 1w3d for 7+3=10 days. )
record-tests:
  # The test results are placed here in JUnit XML format
  result_dir: launchable-test-result

[awilkes]

I don't know why the lint fails for 3.7.

[shibuiwilliam]

merge to a branch in launchableinc.