[Infrastructure] Bump actions/upload-artifact from 6 to 7 (AliceO2Group#15212)

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Author: dependabot[bot]

.github/workflows/mega-linter.yml

@@ -49,7 +49,7 @@ jobs:
 
       # Upload MegaLinter artifacts
       - name: Archive production artifacts
-        uses: actions/upload-artifact@v6
+        uses: actions/upload-artifact@v7
         if: success() || failure()
         with:
           name: MegaLinter reports