Fix prefast issue in image transforms (#837)

* fix prefast issue in image transforms

* Update image_transforms.hpp

* Update image_transforms.hpp

---------

Co-authored-by: Sayan Shaw <sayanshaw@microsoft.com>
Co-authored-by: Wenbing Li <10278425+wenbingl@users.noreply.github.com>

shared/api/image_transforms.hpp

@@ -53,13 +53,15 @@ inline OrtxStatus convert_to_rgb(const ortc::Tensor<uint8_t>& input, ortc::Tenso
 }
 
 struct Resize {
-  static const std::unordered_map<std::string, int> InterpolationMethods() {
+  static const std::unordered_map<std::string, int>& InterpolationMethods() {
-    return {
+    static std::unordered_map<std::string, int> methods = {
       {"NEAREST", IMAGING_TRANSFORM_NEAREST},
       {"LINEAR", IMAGING_TRANSFORM_BILINEAR},
       {"CUBIC", IMAGING_TRANSFORM_BICUBIC},
       {"LANCZOS", IMAGING_TRANSFORM_LANCZOS}
     };
+    
+    return methods;
   }
 
   OrtxStatus Compute(const ortc::Tensor<uint8_t>& input, ortc::Tensor<uint8_t>& output) {