fix: container image name

- [x] needs to be owner/repo, not just repo (excellent catch @zkoppert, thank you)

Signed-off-by: jmeridth <jmeridth@gmail.com>
Co-authored-by: Zack Koppert <zkoppert@github.com>

Author: jmeridth

.github/pull_request-template.md renamed to .github/pull_request_template.md

@@ -40,7 +40,7 @@
         packages: write
       env:
         REGISTRY: ghcr.io
-        IMAGE_NAME: issue_metrics # different than repo name (underscore instead of dash)
+        IMAGE_NAME: github/issue_metrics # different than repo name (underscore instead of dash)
       steps:
         - name: Set up Docker Buildx
           uses: docker/setup-buildx-action@v3