build: fix build for 0.15.0-dev.1034+bd97b6618

build.zig

@@ -9,9 +9,11 @@ pub fn build(b: *std.Build) void {
     });
 
     const tests = b.addTest(.{
-        .root_source_file = b.path("test/tests.zig"),
-        .target = target,
-        .optimize = optimize,
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("test/tests.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
     });
     tests.root_module.addImport("cbor", cbor_mod);