build: Fix pw_module_tests name

Change-Id: Ie38b3157c5a6f62b616c3c2b125f082cd374de3e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/124499
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Sergio Soares <sergiosoares@google.com>

BUILD.gn

@@ -102,7 +102,7 @@ assert(get_path_info("//", "abspath") == get_path_info(".", "abspath"),
        "Pigweed's top-level BUILD.gn may only be used when building upstream " +
            "Pigweed. To pull all Pigweed code into your build, import " +
            "\$dir_pigweed/modules.gni and create a top-level pw_test_group " +
-           "that depends on the tests in pw_modules_tests. See " +
+           "that depends on the tests in pw_module_tests. See " +
            "https://pigweed.dev/build_system.html for details.")
 
 _update_or_check_modules_lists = {