v1.18-arista

This is the first release that will begin the Github Action to publish to the Github Docker Registry!
Builds will be available on ghcr.io/aristanetworks/oidc-authservice:v1.18-arista.

What's Changed

• .github/workflows: add docker publish on release by @devoxel in #37

Full Changelog: v1.17-arista...v1.18-arista