fix bug in config redaction

[sfowl]

Follow up to ee14d55

Before:

$ ./rapidast.py  --config ./config/config-flags.yaml
INFO:Starting the redaction and dumping process for the configuration file: {config_file_location}
INFO:Created destination directory: ./results/flags-1.0/DAST-20241030-092322-RapiDAST-flags-1.0
INFO:Redacting sensitive information from configuration ./config/config-flags.yaml
Traceback (most recent call last):
  File "/home/sfowler/code/rapidast/./rapidast.py", line 286, in <module>
    run()
  File "/home/sfowler/code/rapidast/./rapidast.py", line 226, in run
    dump_rapidast_redacted_configs(config_file, full_result_dir_path)
  File "/home/sfowler/code/rapidast/./rapidast.py", line 177, in dump_rapidast_redacted_configs
    if not dump_redacted_config(main_config_file_location, destination_dir):
  File "/home/sfowler/code/rapidast/./rapidast.py", line 152, in dump_redacted_config
    if config[key].get("authentication") and config[key]["authentication"].get("parameters"):
AttributeError: 'NoneType' object has no attribute 'get'

After:

$ ./rapidast.py  --config ./config/config-flags.yaml
INFO:Starting the redaction and dumping process for the configuration file: {config_file_location}
INFO:Created destination directory: ./results/flags-1.0/DAST-20241030-092330-RapiDAST-flags-1.0
INFO:Redacting sensitive information from configuration ./config/config-flags.yaml
INFO:Saving redacted configuration to ./results/flags-1.0/DAST-20241030-092330-RapiDAST-flags-1.0/config-flags.yaml
INFO:Redacted configuration saved successfully
INFO:Next scanner: 'zap'
INFO:Preparing ZAP configuration
INFO:ZAP NOT configured with any authentication
INFO:Saved Automation Framework in /tmp/rapidast_zap_fb_5l4xq/workdir/af.yaml
INFO:Running up the ZAP scanner on the host
INFO:Zap: verifying the viability of ZAP
ERROR:zap.sh not found in PATH, is ZAP installed?

[sfowl]

Fixes #231

[ccronca]

lgtm