refactor: clean-up empty test targets

src/main.zig

@@ -281,5 +281,3 @@ pub fn main() !void {
         run_posix();
     }
 }
-
-test "simple test" {}

src/nightwatch_test.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const builtin = @import("builtin");
 const nw = @import("nightwatch");
+const main = @import("main");
 
 // ---------------------------------------------------------------------------
 // RecordedEvent