Update banner (#1205)

* Update banner

* Update README.md

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Co-authored-by: Benjie <benjie@jemjie.com>

Author: martinbonnin

README.md

@@ -1,4 +1,4 @@
-[![GraphQLConf 2025 Banner: September 08-10, Amsterdam. Hosted by the GraphQL Foundation](./assets/graphql.org_conf_2025_.png)](https://graphql.org/conf/2025/?utm_source=github&utm_medium=graphql_js&utm_campaign=readme)
+[![The query language for modern APIs](./assets/banner.png)](https://graphql.org/)
 
 # GraphQL