**Apache Airflow version**: 1.10.8 (Patched with latest AWS Hook)

**Environment**:

- **Cloud provider or hardware configuration**: 4 VCPU 8GB RAM VM
- **OS** (e.g. from /etc/os-release): RHEL 7.7
- **Kernel** (e.g. `uname -a`): Linux 3.10.0-957.el7.x86_64
- **Install tools**:
- **Others**:
The AWS Hook functionality for AssumeRoleWithSAML is not available in this version, we manually added it via patching the hook file.

**What happened**:
We've been using this hook for a while now with this issue, basically sts.assume_role and sts.assume_role_with_saml will return temporary credentials that are only valid for eg 1 hour by default. Eventually with long running operators / hooks / sensors some of them fail because the credentials have expired.

Example error messages
An error occurred (ExpiredTokenException) when calling the AssumeRole operation: Response has expired
An error occurred (ExpiredTokenException) when calling the AssumeRoleWithSAML operation: Response has expired
botocore.exceptions.ClientError: An error occurred (ExpiredTokenException) when calling the <any operation here> operation: The security token included in the request is expired

**What you expected to happen**:

AWS hook should be updated to use boto3 RefreshableCredentials when temporary credentials are in use.

**How to reproduce it**:

Use any of the assume role methods with the AWS Hook, create a session, wait 1 hour (or whatever expiry period applies to your role), and try and use the hook again.

**Anything else we need to know**:

I have a solution, please self-assign this.
airflow/providers/amazon/aws/hooks/base_aws.py
import requests_gssapi
        from lxml import etree
        auth = requests_gssapi.HTTPSPNEGOAuth()
        if 'mutual_authentication' in saml_config:
            mutual_auth = saml_config['mutual_authentication']
            if mutual_auth == 'REQUIRED':
                auth = requests_gssapi.HTTPSPNEGOAuth(requests_gssapi.REQUIRED)
            elif mutual_auth == 'OPTIONAL':
                auth = requests_gssapi.HTTPSPNEGOAuth(requests_gssapi.OPTIONAL)
            elif mutual_auth == 'DISABLED':
                auth = requests_gssapi.HTTPSPNEGOAuth(requests_gssapi.DISABLED)
            else:
                raise NotImplementedError(
                    f'mutual_authentication={mutual_auth} in Connection {self.conn.conn_id} Extra.'
                    'Currently "REQUIRED", "OPTIONAL" and "DISABLED" are supported.'
                    '(Exclude this setting will default to HTTPSPNEGOAuth() ).'