formatting json output from lambda that reads csv from S3

I have a lambda that reads a csv from a bucket:

import boto3
import csv
import json

BUCKET_NAME = 'olaptrader-products'
OBJECT_NAME = 'bats.csv'
LAMBDA_LOCAL_TMP_FILE = '/tmp/bats.csv'

def lambda_handler(event, context):
    s3 = boto3.client('s3')
    s3.download_file(BUCKET_NAME, OBJECT_NAME, LAMBDA_LOCAL_TMP_FILE)
    
    with open(LAMBDA_LOCAL_TMP_FILE,'r') as infile:
        reader = list(csv.reader(infile))
    
    return {
        'body': json.dumps(reader)
    }

The csv in my bucket looks like this:

Ticker  Exchange    Date        Open    High    Low    Close    Volume
6A      BATS        12/2/2021   0.9     0.95    0.83    0.95    1200
6B      BATS        12/3/2021   1       1.3     0.9     1.2     1500
6C      BATS        12/4/2021   1.2     1.3     1.1     1.1     1300

My output from the api gateway that calls this lambda looks like this:

[["Ticker", "Exchange", "Date", "Open", "High", "Low", "Close", "Volume"], ["6A", "BATS", "12/2/2021", "0.9", "0.95", "0.83", "0.95", "1200"], ["6B", "BATS", "12/3/2021", "1", "1.3", "0.9", "1.2", "1500"], ["6C", "BATS", "12/4/2021", "1.2", "1.3", "1.1", "1.1", "1300"]]

However, I want the output to look like this:

[{"Ticker":"6A","Exchange":"BATS","Date":"12/2/2021","Open":0.9,"High":0.95,"Low":0.83,"Close":0.95,"volume":1200},{"Ticker":"6B","Exchange":"BATS","Date":"12/3/2021","Open":1,"High":1.3,"Low":0.9,"Close":1.2,"volume":1500},{"Ticker":"6C","Exchange":"BATS","Date":"12/4/2021","Open":1.2,"High":1.3,"Low":1.1,"Close":1.1,"volume":1300}]

Can anyone advise me how to change the lambda around to achieve this?

Also, I dont know why this 'LAMBDA_LOCAL_TMP_FILE" is there. I dont need this. (got from some other site). Can you tell me how to remove that and still have the lambda work? Thanks alot.

you can try with csv.DictReader function

import boto3
import csv
import json

BUCKET_NAME = 'olaptrader-products'
OBJECT_NAME = 'bats.csv'
LAMBDA_LOCAL_TMP_FILE = '/tmp/bats.csv'

def lambda_handler(event, context):
    s3 = boto3.client('s3')
    s3.download_file(BUCKET_NAME, OBJECT_NAME, LAMBDA_LOCAL_TMP_FILE)
    
    with open(LAMBDA_LOCAL_TMP_FILE,'r') as infile:
        reader = csv.DictReader(infile)
        rows = list(reader)
    
    return {
        'body': json.dumps(rows)
    }