Update verify.yml

Author: DilumAluthge

.github/workflows/verify.yml

@@ -22,4 +22,9 @@ jobs:
       - uses: actions/checkout@v2
         with:
           persist-credentials: false
+      - run: |
+          git clone https://github.com/staticfloat/cryptic-buildkite-plugin.git
+          cd cryptic-buildkite-plugin
+          git checkout sf/group_capable
+          cd ..
       - run: make verify_treehashes