ci: Fix valgrind --gen-suppressions argument

It was asking one by one if user wanted to gen suppressions.
For CI it can't be interactive

.github/workflows/valgrind-leakcheck.yml

@@ -41,4 +41,4 @@ jobs:
         run: cmake --build build-dev6 --parallel
 
       - name: Run valgrind
-        run: valgrind --leak-check=full --show-leak-kinds=all --gen-suppressions=yes --error-exitcode=1 --exit-on-first-error=yes --suppressions=./valgrind.sup ./build-dev6/bin/qtwidgets_leak_test -platform offscreen
+        run: valgrind --leak-check=full --show-leak-kinds=all --gen-suppressions=all --error-exitcode=1 --exit-on-first-error=yes --suppressions=./valgrind.sup ./build-dev6/bin/qtwidgets_leak_test -platform offscreen