feat: prefix for deploying in subpath

[redzioch]

Purpose

When go-httpbin is served using subpath (eg. https://server.url/subpath) you need to provide PREFIX environmental variable. Without it, links on main page won't be working properly. According to go-httpbin docs:

PREFIX Prefix of path to listen on (must start with slash and does not end with slash)

With prefix you need to update probes accordingly.

Changes

• added appConfig.prefix value
• passed it as $ENV.PREFIX to container
• updated probes paths

Testing

Deployed and tested on my dev environment

Code Author Checklist

• Bump the chart version (Chart.yaml -> version)
• JSON Schema updated (values.schema.json)
• Update README.md via helm-docs (or make prep)
• Run pre-commit run --all-files via pre-commit (or make prep)
• Update Artifacthub annotation (Chart.yaml -> artifacthub.io/changes, artifacthub.io/images)