fix type mismatch in std.net.StreamServer

Parameter in std.os.listen is u31.

Fixes #6775

Author: johnLate

lib/std/net.zig

@@ -1573,7 +1573,7 @@ fn dnsParseCallback(ctx: dpc_ctx, rr: u8, data: []const u8, packet: []const u8)
 
 pub const StreamServer = struct {
     /// Copied from `Options` on `init`.
-    kernel_backlog: u32,
+    kernel_backlog: u31,
     reuse_address: bool,
 
     /// `undefined` until `listen` returns successfully.
@@ -1585,7 +1585,7 @@ pub const StreamServer = struct {
         /// How many connections the kernel will accept on the application's behalf.
         /// If more than this many connections pool in the kernel, clients will start
         /// seeing "Connection refused".
-        kernel_backlog: u32 = 128,
+        kernel_backlog: u31 = 128,
 
         /// Enable SO_REUSEADDR on the socket.
         reuse_address: bool = false,