add missing typing in buffer value handling

main.py

@@ -21,7 +21,7 @@ aws_env = os.environ['AWS_ENV']
 aws_region = 'eu-central-1'
 temp_dir = '/tmp/'
 # Declare buffer for nicer cuts as float
-cutout_buffer = os.environ['S3_BUFFER_VALUE']
+cutout_buffer = float(os.environ['HF_BUFFER_VALUE'])
 # Initialize an S3 client
 s3_client = boto3.client('s3', aws_access_key_id=aws_access_key_id, aws_secret_access_key=aws_secret_access_key, region_name=aws_region)