fix: revert hashstructure to v0.6.0 to keep artifact IDs stable (#5364)

* fix: revert hashstructure to v0.6.0 to keep artifact IDs stable

hashstructure v1 changed `SlicesAsSets` hashing (every slice now gets a finalizing hash pass, and duplicate elements are deduplicated), which changed nearly every artifact ID syft produces.

- pin `github.com/gohugoio/hashstructure` back to v0.6.0 and have dependabot ignore major bumps
- make the aggregate `Unit tests` job fail when a dependency fails; previously it was skipped, which satisfies the required check and let #5277 auto-merge with failing unit tests

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* ci: fail unit test gate on any failed, cancelled, or skipped dependency

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* ci: require every unit test dependency to succeed

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

.github/workflows/validations.yaml

@@ -51,8 +51,19 @@ jobs:
     name: "Unit tests"
     runs-on: ubuntu-latest
     needs: [Unit-Test-Linux, Unit-Test-Windows]
+    # a skipped job satisfies a required check, so this job must always run and fail explicitly
+    # unless every dependency succeeded (otherwise a failing PR can still be auto-merged)
+    if: ${{ always() }}
     steps:
-      - run: echo All unit tests passed!
+      - name: Require all unit test jobs to succeed
+        env:
+          NEEDS: ${{ toJSON(needs) }}
+        run: |
+          echo "$NEEDS" | jq -e 'length > 0 and all(.[]; .result == "success")' > /dev/null || {
+            echo "$NEEDS" | jq -r 'to_entries[] | "\(.key): \(.value.result)"'
+            exit 1
+          }
+          echo All unit tests passed!
 
   Unit-Test-Linux:
     name: "Unit tests (Linux)"