[3.13] gh-149861: Fix rule in match statement case_block PEG grammar (#150512)

(cherry picked from commit 99c254e)

Co-authored-by: Ivy Xu <fakeshadow1337@gmail.com>

Author: miss-islington

Doc/reference/compound_stmts.rst

@@ -613,7 +613,7 @@ The match statement is used for pattern matching.  Syntax:
    match_stmt: 'match' `subject_expr` ":" NEWLINE INDENT `case_block`+ DEDENT
    subject_expr: `flexible_expression` "," [`flexible_expression_list` [',']]
                : | `assignment_expression`
-   case_block: 'case' `patterns` [`guard`] ":" `!block`
+   case_block: 'case' `patterns` [`guard`] ":" `suite`
 
 .. note::
    This section uses single quotes to denote