tamp when file last accessed

* :changed - timestamp when file last changed (permissions changed)

* :modified - timestamp when file last modified (content changed)
</pre><a href="https://janetdocs.org/os/stat">Community Examples</a></div><hr><div class="binding"><span id="os/strftime" class="binding-sym">os/strftime</span> <span class="binding-type">cfunction</span> <span class="binding-type"><a href="https://github.com/janet-lang/janet/blob/4e5889e/src/core/os.c#L1667">source</a></span> <pre class="bindin