DOC: Fix missing read_parquet from list of fns with new keyword arg dtype_backend (#52486)

`read_parquet` also has new kwd `dtype_backend`

Doc fix for whats new v2.0.0.rst

Author: alexmalins

doc/source/whatsnew/v2.0.0.rst

@@ -120,6 +120,7 @@ The following functions gained a new keyword ``dtype_backend`` (:issue:`36712`)
 * :func:`read_sql`
 * :func:`read_sql_query`
 * :func:`read_sql_table`
+* :func:`read_parquet`
 * :func:`read_orc`
 * :func:`read_feather`
 * :func:`read_spss`