fix(security-scans): use step outcome instead of conclusion for snyk (#392)

The Snyk step uses `continue-on-error: true`, which overrides
`conclusion` to `success` even when Snyk fails. The downstream steps
checking `steps.snyk.conclusion` would always run, causing the pipeline
to break when Snyk didn't produce a sarif file.

Use `outcome` instead, which reflects the actual result of the step
before `continue-on-error` is applied.

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>

Author: mnencia

.github/actions/security-scans/action.yml

@@ -51,14 +51,14 @@ runs:
         args: --severity-threshold=high --file=${{ inputs.dockerfile }}
 
     - name: Replace sarif security-severity invalid values
-      if: ${{ steps.snyk.conclusion == 'success' }}
+      if: ${{ steps.snyk.outcome == 'success' }}
       shell: bash
       run: |
         sed -i 's/"security-severity": "null"/"security-severity": "0"/g' snyk.sarif
         sed -i 's/"security-severity": "undefined"/"security-severity": "0"/g' snyk.sarif
 
     - name: Upload result to GitHub Code Scanning
       uses: github/codeql-action/upload-sarif@45cbd0c69e560cd9e7cd7f8c32362050c9b7ded2 # v4
-      if: ${{ steps.snyk.conclusion == 'success' }}
+      if: ${{ steps.snyk.outcome == 'success' }}
       with:
         sarif_file: snyk.sarif