As reported in https://github.com/localstack/localstack/issues/6659#issuecomment-1630932643_, `HeadObject` does not respect `ChecksumMode`. 


```shell
at 09:31:57 ➜ AWS_DEFAULT_REGION=us-west-1 aws --endpoint-url=http://localhost:4566 s3api create-bucket --bucket test-bucket --create-bucket-configuration LocationConstraint=us-west-1
{
    "Location": "http://test-bucket.s3.localhost.localstack.cloud:4566/"
}

at 09:32:13 ➜ aws --endpoint-url=http://localhost:4566 s3api put-object --bucket test-bucket --key file.json --body README.md --checksum-algorithm SHA256
{
    "ETag": "\"4bb2f1387449d690bff6336ea255909c\"",
    "ChecksumSHA256": "bzOikXXMUqRTCrpVq7Pt7LjJ0fjR3ccUfM19S/gnfqA="
}

# SHA256 missing here
at 09:32:20 ➜ aws --endpoint-url=http://localhost:4566 s3api head-object --bucket test-bucket --key file.json --checksum-mode Enabled
{
    "AcceptRanges": "bytes",
    "LastModified": "2023-07-11T13:32:15+00:00",
    "ContentLength": 1455,
    "ETag": "\"4bb2f1387449d690bff6336ea255909c\"",
    "ContentType": "binary/octet-stream",
    "Metadata": {}
}
```

Note the equivalent response from S3 actual includes the SHA256 value

```shell
at 10:21:23 ➜ aws s3api head-object --bucket test-bucket --key file.json --checksum-mode Enabled
{
    "AcceptRanges": "bytes",
    "Expiration": "expiry-date=\"Thu, 13 Jul 2023 00:00:00 GMT\", rule-id=\"all\"",
    "LastModified": "2023-07-11T14:21:09+00:00",
    "ContentLength": 1956,
    "ChecksumSHA256": "bj7fqCqtaF95M1ULwQRDJuHbL/Xd9NVMH6pua9OINcc=",
    "ETag": "\"f4be535d45019a4408dd5369986919f8\"",
    "ContentEncoding": "",
    "ContentType": "binary/octet-stream",
   
    "Metadata": {},
    
}
```

_Originally posted by @bdurrani in https://github.com/localstack/localstack/issues/6659#issuecomment-1630932643_
            
src_moto_bucket, key=src_key, version_id=src_version_id
        )
        
        condition = None
        source_object_last_modified = source_key_object.last_modified.replace(
            tzinfo=ZoneInfo("GMT")
        )
        if (cs_if_match := request.get("CopySourceIfMatch")) and source_key_object.etag.strip(
            '"'
        ) != cs_if_match.strip('"'):
            condition = "x-amz-copy-source-If-Match"
        elif (
            cs_id_unmodified_since := request.get("CopySourceIfUnmodifiedSince")
        ) and source_object_last_modified > cs_id_unmodified_since:
            condition = "x-amz-copy-source-If-Unmodified-Since"
        elif (
            cs_if_none_match := request.get("CopySourceIfNoneMatch")
        ) and source_key_object.etag.strip('"') == cs_if_none_match.strip('"'):
            condition = "x-amz-copy-source-If-None-Match"
        elif (
            cs_id_modified_since := request.get("CopySourceIfModifiedSince")
        ) and source_object_last_modified < cs_id_modified_since < datetime.datetime.now(
            tz=ZoneInfo("GMT")
        ):
            condition = "x-amz-copy-source-If-Modified-Since"
        if condition:
            raise PreconditionFailed(
                "At least one of the pre-conditions you specified did not hold",
                Condition=condition,
            )