### Please describe the problem.

When I attempt to create a S3 remote against my garage[1] cluster, it errors with the following:

```
$ git annex initremote garage type=S3 encryption=none host=my-s3-endpoint.domain.com protocol=https bucket=git-annex requeststyle=path datacenter=garage signature=v4
initremote garage (checking bucket...) (creating bucket in garage...)
git-annex: S3Error {s3StatusCode = Status {statusCode = 400, statusMessage = "Bad Request"}, s3ErrorCode = "AuthorizationHeaderMalformed", s3ErrorMessage = "Authorization header malformed, expected scope: 20230118/my-s3-endpoint.domain.com/s3/aws4_request", s3ErrorResource = Just "/git-annex/", s3ErrorHostId = Nothing, s3ErrorAccessKeyId = Nothing, s3ErrorStringToSign = Nothing, s3ErrorBucket = Nothing, s3ErrorEndpointRaw = Nothing, s3ErrorEndpoint = Nothing}
failed
initremote: 1 failed

$ git annex initremote garage type=S3 encryption=none host=my-s3-endpoint.domain.com protocol=https bucket=git-annex requeststyle=path datacenter=garage
initremote garage (checking bucket...) (creating bucket in garage...)
git-annex: S3Error {s3StatusCode = Status {statusCode = 400, statusMessage = "Bad Request"}, s3ErrorCode = "InvalidRequest", s3ErrorMessage = "Bad request: Unsupported authorization method", s3ErrorResource = Just "/git-annex/", s3ErrorHostId = Nothing, s3ErrorAccessKeyId = Nothing, s3ErrorStringToSign = Nothing, s3ErrorBucket = Nothing, s3ErrorEndpointRaw = Nothing, s3ErrorEndpoint = Nothing}
failed
initremote: 1 failed
```

Garage appears to support v4 signatures: https://garagehq.deuxfleurs.fr/documentation/reference-manual/s3-compatibility/#high-level-features - and other S3 tooling works against the endpoint.


### What version of git-annex are you using? On what operating system?

Fedora Silverblue 37 / git-annex-10.20221212-1.fc37.x86_64

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

Yes, many years ago - now trying to get it up and running with my self-hosted S3 endpoint.

[1]: https://garagehq.deuxfleurs.fr/
