Old which on circleci, fallback to command (#48)

ls_pre_commit_hooks/poetry-run.sh

@@ -1,6 +1,6 @@
 #!/bin/bash -e
 
-if ! which -s poetry; then
+if ! [ -x "$(command -v poetry)" ]; then
   echo 'poetry command not found'
   echo 'See https://python-poetry.org/docs/#installation for installation instructions.'
   exit 1