ci: update setup-just to use v3 from hash (#4)

Author: shoenig

.github/workflows/ci.yaml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
-      - uses: extractions/setup-just@v2
+      - uses: extractions/setup-just@e33e0265a09d6d736e2ee1e0eb685ef1de4669ff
       - uses: actions/setup-go@v5
         with:
           go-version-file: go.mod