bpo-40958: Avoid 'possible loss of data' warning on Windows (GH-20970)

(cherry picked from commit 861efc6e8fe7f030b1e193989b13287b31385939)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
diff --git a/Parser/pegen/pegen.c b/Parser/pegen/pegen.c
index e63e5a8..a1a59ae 100644
--- a/Parser/pegen/pegen.c
+++ b/Parser/pegen/pegen.c
@@ -397,7 +397,7 @@
     }
 
     if (p->start_rule == Py_file_input) {
-        error_line = PyErr_ProgramTextObject(p->tok->filename, lineno);
+        error_line = PyErr_ProgramTextObject(p->tok->filename, (int) lineno);
     }
 
     if (!error_line) {