Translate OpenTelemetry Python exceptions

# Description

Exceptions captured on Python OpenTelemetry traces are not reported in Elastic APM GUI.

See https://github.com/elastic/apm-server/blob/v7.13.4/processor/otel/exceptions.go#L85-L91
```go
func setExceptionStacktrace(s, language string, out *model.Exception) error {
switch language {
case "java":
return setJavaExceptionStacktrace(s, out)
}
return fmt.Errorf("parsing %q stacktraces not implemented", language)
}
```

# See Also

* elastic/apm-server#5795
* elastic/apm-server#5800