[3.10] bpo-44257: fix "assigment_expr" typo + regenerate the grammar,…

… and remove unused imports (GH-29393) (GH-29395)

Co-authored-by: Wim Glenn <wglenn@jumptrading.com>.
(cherry picked from commit 762173c)

Co-authored-by: wim glenn <wim.glenn@gmail.com>

Grammar/python.gram

@@ -512,11 +512,11 @@ star_named_expression[expr_ty]:
     | named_expression
 
 
-assigment_expression[expr_ty]:
+assignment_expression[expr_ty]:
     | a=NAME ':=' ~ b=expression { _PyAST_NamedExpr(CHECK(expr_ty, _PyPegen_set_expr_context(p, a, Store)), b, EXTRA) }
 
 named_expression[expr_ty]:
-    | assigment_expression
+    | assignment_expression
     | invalid_named_expression
     | expression !':='
 
@@ -708,7 +708,7 @@ group[expr_ty]:
     | '(' a=(yield_expr | named_expression) ')' { a }
     | invalid_group
 genexp[expr_ty]:
-    | '(' a=( assigment_expression | expression !':=') b=for_if_clauses ')' { _PyAST_GeneratorExp(a, b, EXTRA) }
+    | '(' a=( assignment_expression | expression !':=') b=for_if_clauses ')' { _PyAST_GeneratorExp(a, b, EXTRA) }
     | invalid_comprehension
 set[expr_ty]: '{' a=star_named_expressions '}' { _PyAST_Set(a, EXTRA) }
 setcomp[expr_ty]:
@@ -747,7 +747,7 @@ arguments[expr_ty] (memo):
     | a=args [','] &')' { a }
     | invalid_arguments
 args[expr_ty]:
-    | a[asdl_expr_seq*]=','.(starred_expression | ( assigment_expression | expression !':=') !'=')+ b=[',' k=kwargs {k}] {
+    | a[asdl_expr_seq*]=','.(starred_expression | ( assignment_expression | expression !':=') !'=')+ b=[',' k=kwargs {k}] {
         _PyPegen_collect_call_seqs(p, a, b, EXTRA) }
     | a=kwargs { _PyAST_Call(_PyPegen_dummy_name(p),
                           CHECK_NULL_ALLOWED(asdl_expr_seq*, _PyPegen_seq_extract_starred_exprs(p, a)),