Set action.yml to use :2.1.3

rather than latest.

Manually ran the workflow to build and push Docker image:

https://github.com/users/solvaholic/packages/container/octodns-sync/2427847?tag=12725f0da650801840dc01551a776845c3d644e6

Added :latest, :2.1.3, and :2 tags to that image, and pushed them to ghcr.io:

https://github.com/users/solvaholic/packages/container/package/octodns-sync

action.yml

@@ -24,7 +24,7 @@ inputs:
 
 runs:
   using: 'docker'
-  image: 'docker://ghcr.io/solvaholic/octodns-sync:latest'
+  image: 'docker://ghcr.io/solvaholic/octodns-sync:2.1.3'
   env:
     ADD_PR_COMMENT: ${{ inputs.add_pr_comment }}
     PR_COMMENT_TOKEN: ${{ inputs.pr_comment_token }}