gguf : expose the gguf_type enum through the API for now

ggml.h

@@ -1619,6 +1619,20 @@ extern "C" {
     // gguf
     //
 
+    // TODO: can be removed if the API is extended for writing
+    enum gguf_type {
+        GGUF_TYPE_UINT8   = 0,
+        GGUF_TYPE_INT8    = 1,
+        GGUF_TYPE_UINT16  = 2,
+        GGUF_TYPE_INT16   = 3,
+        GGUF_TYPE_UINT32  = 4,
+        GGUF_TYPE_INT32   = 5,
+        GGUF_TYPE_FLOAT32 = 6,
+        GGUF_TYPE_BOOL    = 7,
+        GGUF_TYPE_STRING  = 8,
+        GGUF_TYPE_ARRAY   = 9,
+    };
+
     struct gguf_context;
 
     struct gguf_init_params {