chore(Files): explicitly cast mtime in View

[joshtrichards]

• Resolves: #

Summary

To solve this for now:

--

1 test triggered 1 PHP deprecation:

1) /home/runner/work/server/server/lib/private/Files/Storage/Wrapper/Wrapper.php:159
Implicit conversion from float 500.5 to int loses precision

Triggered by:

* Test\Files\ViewTest::testTouchFloat
  /home/runner/work/server/server/tests/lib/Files/ViewTest.php:598

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)