Update for new zig IO

`test/tests.zig` fails after ziglang/zig#25592 was
merged in. This just ensures that Io is passed, it might not be the
ideal solution.
`build.zig` was also failing due to new color parameter.

Author: esensar

build.zig

@@ -570,12 +570,12 @@ const ZiglingStep = struct {
 
         // Render compile errors at the bottom of the terminal.
         // TODO: use the same ttyconf from the builder.
-        const ttyconf: std.Io.tty.Config = if (use_color_escapes)
-            .escape_codes
+        const color: std.zig.Color = if (use_color_escapes)
+            .on
         else
-            .no_color;
+            .off;
         if (self.step.result_error_bundle.errorMessageCount() > 0) {
-            self.step.result_error_bundle.renderToStdErr(.{ .ttyconf = ttyconf });
+            self.step.result_error_bundle.renderToStdErr(.{}, color);
         }
     }
 };

test/tests.zig

@@ -161,7 +161,9 @@ const CheckNamedStep = struct {
         );
         defer stderr_file.close();
 
-        var stderr = stderr_file.readerStreaming(&.{});
+        var threaded: std.Io.Threaded = .init_single_threaded;
+        const io = threaded.io();
+        var stderr = stderr_file.readerStreaming(io, &.{});
         {
             // Skip the logo.
             const nlines = mem.count(u8, root.logo, "\n");
@@ -213,7 +215,9 @@ const CheckStep = struct {
         );
         defer stderr_file.close();
 
-        var stderr = stderr_file.readerStreaming(&.{});
+        var threaded: std.Io.Threaded = .init_single_threaded;
+        const io = threaded.io();
+        var stderr = stderr_file.readerStreaming(io, &.{});
         for (exercises) |ex| {
             if (ex.number() == 1) {
                 // Skip the logo.