fence_aws: clarify Python version requirement for boto3 dependency

### Description
In environments like SLES 15, boto3 is only available for a specific Python version (e.g. python3.11), while fence_aws may still use a different interpreter (/usr/bin/python3).

This can lead to runtime errors such as:
NameError: name 'boto3' is not defined

### Suggestion
It would be helpful to clarify:
- the required Python version
- or the expected boto3 package variant
- or ensure the script uses a compatible interpreter

### Environment
- OS: SLES 15 SP7
- fencing: fence_aws

```markdown
### Error output
```bash
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ Traceback (most recent call last): ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ File "/usr/sbin/fence_aws", line 261, in ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ main() ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ File "/usr/sbin/fence_aws", line 232, in main ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ boto3.set_stream_logger('boto3',logging.INFO) ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_op_output) info: fence_aws_monitor_2of2[2595063] error output [ NameError: name 'boto3' is not defined ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ Traceback (most recent call last): ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ File "/usr/sbin/fence_aws", line 261, in ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ main() ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ File "/usr/sbin/fence_aws", line 232, in main ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ boto3.set_stream_logger('boto3',logging.INFO) ]
Jun 11 11:52:52.079 HDB01 pacemaker-fenced [19663] (log_action) warning: fence_aws[2595063] stderr: [ NameError: name 'boto3' is not defined ]
---

Start with /usr/sbin/fence_aws at lines 232 and 261, then inspect how the agent is invoked with /usr/bin/python3 and how boto3 is made available. Verify the failure on SLES 15 SP7 and define whether the required Python version, boto3 package variant, or interpreter compatibility resolves the traceback.

Written by the indexing model from the issue text.