[Improvement] add vector_dimension configuration in embedder config (#1192)

Co-authored-by: Deven Patel <deven298@yahoo.com>

embedchain/embedder/openai.py

@@ -32,4 +32,5 @@ class OpenAIEmbedder(BaseEmbedder):
                 model_name=self.config.model,
             )
         self.set_embedding_fn(embedding_fn=embedding_fn)
-        self.set_vector_dimension(vector_dimension=VectorDimensions.OPENAI.value)
+        vector_dimension = self.config.vector_dimension or VectorDimensions.OPENAI.value
+        self.set_vector_dimension(vector_dimension=vector_dimension)