Fix: update spir-v mutant number

.github/workflows/cxx_apps.sh

@@ -157,7 +157,7 @@ pushd SPIRV-Tools
   ./build/test/val/test_val_fghijklmnop
   ./build/test/val/test_val_rstuvw
   NUM_MUTANTS=`python3 ${DREDD_ROOT}/scripts/query_mutant_info.py mutation-info.json --largest-mutant-id`
-  EXPECTED_NUM_MUTANTS=68821
+  EXPECTED_NUM_MUTANTS=68841
   if [ ${NUM_MUTANTS} -ne ${EXPECTED_NUM_MUTANTS} ]
   then
      echo "Found ${NUM_MUTANTS} mutants when mutating the SPIR-V validator source code. Expected ${EXPECTED_NUM_MUTANTS}. If Dredd changed recently, the expected value may just need to be updated, if it still looks sensible. Otherwise, there is likely a problem."