Update MNN script

tools/mnn

@@ -11,7 +11,6 @@ clean() {
 sync() {
     echo "mnn sync"
     mkdir -p "./third_party/source/mnn/schema/default"
-    curl --silent --location --output "./third_party/source/mnn/schema/default/BasicOptimizer.fbs" "https://github.com/alibaba/MNN/blob/master/schema/default/BasicOptimizer.fbs?raw=true"
     curl --silent --location --output "./third_party/source/mnn/schema/default/CaffeOp.fbs" "https://github.com/alibaba/MNN/blob/master/schema/default/CaffeOp.fbs?raw=true"
     curl --silent --location --output "./third_party/source/mnn/schema/default/GpuLibrary.fbs" "https://github.com/alibaba/MNN/blob/master/schema/default/GpuLibrary.fbs?raw=true"
     curl --silent --location --output "./third_party/source/mnn/schema/default/MNN.fbs" "https://github.com/alibaba/MNN/blob/master/schema/default/MNN.fbs?raw=true"