Exclude single_include from flawfinder scan (#5912)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/flawfinder.yml

@@ -43,7 +43,8 @@ jobs:
       - name: flawfinder_scan
         uses: david-a-wheeler/flawfinder@c4216b74cf2639ffa98503768bd6e4299b5440c9 # v2.0.20
         with:
-          arguments: '--sarif ./'
+          # single_include/ is omitted: it is generated from include/ and would report every finding twice
+          arguments: '--sarif ./cmake ./docs ./include ./src ./tests ./tools'
           output: 'flawfinder_results.sarif'
 
       - name: Upload analysis results to GitHub Security tab