Fix C4267 warning (size_t -> int) convertion

tiny_gltf.h

diff --git a/tiny_gltf.h b/tiny_gltf.h
index 89525bc..d1d22e7 100644
--- a/tiny_gltf.h
+++ b/tiny_gltf.h
@@ -3094,7 +3094,7 @@
     if (componentType >= TINYGLTF_COMPONENT_TYPE_BYTE &&
         componentType <= TINYGLTF_COMPONENT_TYPE_DOUBLE) {
       // OK
-      accessor->componentType = componentType;
+      accessor->componentType = int(componentType);
     } else {
       std::stringstream ss;
       ss << "Invalid `componentType` in accessor. Got " << componentType