message: bumping fallback version to v3.1.1
diff: import os
  import subprocess
  -FALLBACK_VERSION = "v3.1.0" # Keep up-to-date on release tag
  +FALLBACK_VERSION = "v3.1.1" # Keep up-to-date on release tag
  def get_version_str(working_dir, fallback=FALLBACK_VERSION):
  