fix: helm chart security context rendering if empty

[botchk]

Closes #

📑 Description

When .Values.deployment.securityContext is empty ({}), the helm installation fails with

Error: YAML parse error on k8sgpt/templates/deployment.yaml: error converting YAML to JSON: yaml: lin
e 24: mapping values are not allowed in this context                                                 
                                                                                                     
Use --debug flag to render out invalid YAML 

This fixes the rendering.

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

ℹ Additional Information

[arbreezy]

thanks @botchk