Call cargo by absolute path (PATH did not carry over between steps)

.gitea/workflows/sandbox.yml

@@ -43,6 +43,6 @@ jobs:
       - name: Test
         run: |
           set -o pipefail          # without this a failing build looks green
-          # GITHUB_PATH from the previous step did not propagate in runner v5.2.2
-          export PATH="$HOME/.cargo/bin:$PATH"
-          cargo test 2>&1 | tail -4
+          CARGO="$HOME/.cargo/bin/cargo"
+          echo "HOME=$HOME  cargo there: $([ -x "$CARGO" ] && echo yes || echo no)"
+          "$CARGO" test 2>&1 | tail -4