ci: add Semgrep OSS scanning workflow
## Summary Port from https://github.com/cloudflare/cloudflared/pull/1639 to GitLab
J
João "Pisco" Fernandes committed
f76f75b44946a5d060ef4b95b02ea2296d20f9ad
Parent: 5c66bd6
## Summary Port from https://github.com/cloudflare/cloudflared/pull/1639 to GitLab