(core) correct docker image name from gristlabs/grist-core to gristlabs/grist

Summary: The docker image is "grist" not "grist-core"

Test Plan: tested on a fork

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3158

.github/workflows/docker.yml

@@ -18,5 +18,5 @@ jobs:
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
-          repository: ${{ github.repository }}
+          repository: ${{ github.repository_owner }}/grist
           tag_with_ref: true

.github/workflows/docker_latest.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
-          repository: ${{ github.repository }}
+          repository: ${{ github.repository_owner }}/grist
           tags: latest
       - name: Update latest branch
         uses: ad-m/github-push-action@8407731efefc0d8f72af254c74276b7a90be36e1