Including the `Range` header on S3 requests triggers a `502 Bad Gateway` when localstack is run with SSL.

Sample test that demonstrates the issue:
```python
import logging
import io
import os

import boto3

logging.basicConfig(level=logging.INFO)


def test_range_s3():
    s3 = boto3.client('s3', endpoint_url='https://localhost:4572', use_ssl=True, verify=False)

    bucket = 'localstack-s3-range'
    obj_name = 'sample.bin'
    s3.create_bucket(Bucket=bucket)

    chunk_size = 1024

    with io.BytesIO() as data:
        data.write(os.urandom(chunk_size * 2))
        logging.info('Uploading object (size=%d)', data.getbuffer().nbytes)
        data.seek(0)
        s3.upload_fileobj(data, bucket, obj_name)

    range_header = f'bytes=0-{chunk_size - 1}'
    logging.info('Downloading using Range header: %s', range_header)
    
    # this will raise an exception
    # botocore.exceptions.ClientError: An error occurred (502) when calling the GetObject operation (reached max retries: 4): Bad Gateway
    resp = s3.get_object(Bucket=bucket, Key=obj_name, Range=range_header)
    
    content = resp['Body'].read()
    assert len(content) == chunk_size
```

This is a fairly recent regression:

Running against `localstack/localstack:latest` will fail using SSL but pass without SSL. 
Running against `localstack/localstack:0.10.6` will pass using SSL as well as without SSL.

I am guessing changes from either #1887 or #1906 broke this since those were related to `Range` functionality, but have not bisected to be sure.
"""Add Last-Modified header with current time
    (if the response content is an XML containing <LastModified>, add that instead)"""
    time_format = '%a, %d %b %Y %H:%M:%S GMT'  
    try:
        if content:
            last_modified_str = re.findall(r'<LastModified>([^<]*)</LastModified>', content)
            if last_modified_str:
                last_modified_str = last_modified_str[0]
                last_modified_time_format = dateutil.parser.parse(last_modified_str).strftime(time_format)
                response.headers['Last-Modified'] = last_modified_time_format
    except TypeError as err:
        LOGGER.debug('No parsable content: %s' % err)
    except ValueError as err:
        LOGGER.error('Failed to parse LastModified: %s' % err)
    except Exception as err:
        LOGGER.error('Caught generic exception (parsing LastModified): %s' % err)
    
    try:
        if response.headers.get('Last-Modified', '') == '':
            response.headers['Last-Modified'] = datetime.datetime.now().strftime(time_format)
    except Exception as err:
        LOGGER.error('Caught generic exception (setting LastModified header): %s' % err)
def append_list_objects_marker(method, path, data, response):