Changed action to only run in main repository (#955)

Co-authored-by: Nicholas Tindle <nicktindle@outlook.com>

Author: stormofice

.github/workflows/publish_container.yml

@@ -6,6 +6,7 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    if: github.repository == 'algorithm-archivists/algorithm-archive'
     steps:
     - uses: actions/checkout@master
     - name: Publish to Registry