fix: use stdlib zipfile in test instead of python-docx

Address Copilot review: python-docx isn't in the base rootfs, so the
test would fail with ModuleNotFoundError. Use stdlib zipfile.ZipFile
directly to exercise the ZipInfo.__init__ monkey-patch.

Signed-off-by: danbugs <danilochiarlone@gmail.com>

Author: danbugs

host/tests/pyhl_runtime.rs

@@ -127,7 +127,7 @@ fn runtime_zipinfo_patch_survives_cleanup() {
         return;
     };
     let timing = rt
-        .run_code("from docx import Document\ndoc = Document()\nprint('ok')")
+        .run_code("import zipfile, io\nbuf = io.BytesIO()\nwith zipfile.ZipFile(buf, 'w') as z:\n    z.writestr('test.txt', 'hello')\nprint('ok')")
         .unwrap();
     assert_eq!(timing.exit_code, 0);
 }