fix: explicit pin of upstream c7n-left version (#44)

An upstream c7n release caused issues with sinistral-cli, so it was
determined that the default behavior should be to pin to the version
that we have specifically tested with.

Author: johnsca

poetry.lock

@@ -20,7 +20,7 @@ jmespath = "^1.0.1"
 pyjwt = "^2.6.0"
 pyrsistent = "^0.19.3"
 pyyaml = "^6.0"
-c7n-left = "^0.3.22"
+c7n-left = "==0.3.22"
 
 
 [tool.poetry.group.dev.dependencies]