Remove fields [author, title, thumbnail] from _blog.yml (#3151)

* Remove fields `[author, title, thumbnail]` from `_blog.yml`

* Remove `author`, `title`, and `thumbnail` fields from YAML validation schema in `validate-yaml.ts`

* fix upstream

* remove duplicate fields

* Revert "remove duplicate fields"

This reverts commit 55f0366.

* run script

* more validation

* fixes

* fix

* Update thumbnail validation to include .webp format in YAML schema

Author: mishig25

1b-sentence-embeddings.md

@@ -1,5 +1,6 @@
 ---
-title: "Train a Sentence Embedding Model with 1B Training Pairs"
+title: Train a Sentence Embedding Model with 1B Training Pairs
+thumbnail: /blog/assets/32_1b_sentence_embeddings/model.png
 authors:
 - user: asi
   guest: true