Converted MIN_RETENTION_TIME env var to an integer

lambda_ebs_snapshots.py

@@ -9,7 +9,7 @@ a snapshot of all EBS volumes attached to it. It also tags the snapshots for
 deletion after a number of retention days.
 """
 
-MIN_RETENTION_COUNT = os.environ['MIN_RETENTION_COUNT']
+MIN_RETENTION_COUNT = int(os.environ['MIN_RETENTION_COUNT'])
 RETENTION_DAYS_DEFAULT = os.environ['DEFAULT_RETENTION_DAYS']
 SNAPSHOT_TAG = os.environ['SNAPSHOT_TAG']
 RETENTION_TAG = os.environ['RETENTION_TAG']