Please address the comments from this code review:

## Overall Comments
- The `test_package_link_size_default_None` test name is misleading since it sets `size=1234` and asserts that value; consider renaming it (e.g. `test_package_link_size_explicit_value`) to better reflect its purpose.
- In `Link.upload_time`, using `self._upload_time.replace("Z", "+00:00")` will replace all `Z` characters, not just a trailing UTC designator; it would be safer to normalize only a terminal `Z` (e.g. with `endswith("Z")`) before calling `datetime.fromisoformat`.

## Individual Comments

### Comment 1
<location> `tests/packages/utils/test_utils_link.py:3-9` </location>
<code_context>
+    assert link.upload_time is None
+
+
[email protected](
+    ("upload_time", "expected"),
+    [
+        ("2023-06-15T08:30:45Z", datetime(2023, 6, 15, 8, 30, 45, tzinfo=timezone.utc)),
+        (
+            "2022-12-31T23:59:59+00:00",
+            datetime(2022, 12, 31, 23, 59, 59, tzinfo=timezone.utc),
+        ),
+        (
+            "2023-06-15T08:30:45.123456Z",
+            datetime(2023, 6, 15, 8, 30, 45, 123456, tzinfo=timezone.utc),
+        ),
+    ],
+)
+def test_package_link_upload_time(upload_time: str, expected: datetime) -> None:
+    link = Link("https://example.org", upload_time=upload_time)
+
</code_context>

<issue_to_address>
**suggestion (testing):** Consider adding tests for invalid and offsetted `upload_time` values

The current parametrized test nicely covers several valid ISO 8601 formats. To strengthen it, please also add cases for (1) an invalid ISO string (e.g. "not-a-timestamp") to assert `link.upload_time` is `None`, and (2) a timestamp with a non-zero offset (e.g. `"2023-06-15T10:30:45+02:00"`) so offset handling and behavior on older Python versions are exercised and guarded against regressions.

```suggestion
import uuid

from datetime import datetime
from datetime import timezone
from hashlib import sha256

import pytest


@pytest.mark.parametrize(
    ("upload_time", "expected"),
    [
        (
            "2023-06-15T08:30:45Z",
            datetime(2023, 6, 15, 8, 30, 45, tzinfo=timezone.utc),
        ),
        (
            "2022-12-31T23:59:59+00:00",
            datetime(2022, 12, 31, 23, 59, 59, tzinfo=timezone.utc),
        ),
        (
            "2023-06-15T08:30:45.123456Z",
            datetime(2023, 6, 15, 8, 30, 45, 123456, tzinfo=timezone.utc),
        ),
        (
            "2023-06-15T10:30:45+02:00",
            datetime(2023, 6, 15, 8, 30, 45, tzinfo=timezone.utc),
        ),
        ("not-a-timestamp", None),
    ],
)
def test_package_link_upload_time(upload_time: str, expected: object) -> None:
    link = Link("https://example.org", upload_time=upload_time)

    assert link.upload_time == expected

    assert link.yanked == expected_yanked
```
</issue_to_address>