**Apache Airflow version**:
2.1.0

**What happened**:
When printing emoji to a DAG log, the Airflow dashboard fails to display the entire log.
When checking the output log in the Airflow dashboard, the following error message appears:

> *** Failed to load local log file: /tmp/dag_name/task_name/2021-07-06T10:49:18.136953+00:00/1.log
> *** 'ascii' codec can't decode byte 0xf0 in position 3424: ordinal not in range(128)

**What you expected to happen**:
The log should be displayed.

<!-- What do you think went wrong? -->


**How to reproduce it**:
Insert the following into any Python DAG, then run it.
`print("💼")`

**How often does this problem occur?**
Every log with an emoji in it prints an error.

**Why would anyone even want to print emoji in their logs?**
When they're part of the dataset you're processing.
airflow/utils/log/file_task_handler.py
response = httpx.get(
                    url, timeout=timeout, headers={'Authorization': signer.dumps(log_relative_path)}
                )
                response.encoding = "utf-8"
                if response.status_code == 403:
                    log += (
                        "*** !!!! Please make sure that all your Airflow components (e.g. "
                        "schedulers, webservers and workers) have"
                        " the same 'secret_key' configured in 'webserver' section !!!!!\n***"
                    )
                    log += (
                        "*** See more at https://airflow.apache.org/docs/apache-airflow/"
                        "stable/configurations-ref.html#secret-key\n***"
                    )
                
                response.raise_for_status()
                log += '\n' + response.text
            except Exception as e:
                log += f"*** Failed to fetch log file from worker. {str(e)}\n"
        return log, {'end_of_log': True}
    def read(self, task_instance, try_number=None, metadata=None):
        """
        Read logs of given task instance from local machine.
        :param task_instance: task instance object
        :param try_number: task instance try_number to read logs from. If None
                           it returns all logs separated by try_number
        :param metadata: log metadata,
                         can be used for steaming log reading and auto-tailing.
        :return: a list of listed tuples which order log string by host
        """