Update Helm release oauth2-proxy to v7.12.8

No problems deploying to Proxmox VE K3s Kubernetes cluster via Helm Chart and Flux V2 reconciliation in a GitOps approach with dependency update facilitated by Mend's Renovate Bot.

This MR contains the following updates:

Package	Update	Change
oauth2-proxy (source)	patch	`7.12.7` -> `7.12.8`

Release Notes

oauth2-proxy/manifests (oauth2-proxy)

`v7.12.8`

Compare Source

A reverse proxy that provides authentication with Google, Github or other providers

What's Changed

chore: bump oauth2-proxy appVersion to v7.8.2 by @tuunit in https://github.com/oauth2-proxy/manifests/pull/298

Full Changelog: https://github.com/oauth2-proxy/manifests/compare/oauth2-proxy-7.12.7...oauth2-proxy-7.12.8