Adjust index page Cache-Control headers

This changes the `Cache-Control` value for index pages from:
`no-cache,no-store,must-revalidate`

...to:
`max-age=600, public`

In order to allow the pages to be cached for up to 10 minutes.

The new value was chosen so that it matches that returned for
PyPI index pages:

```
$ curl -sSI https://pypi.org/simple/ | rg cache-control
cache-control: max-age=600, public
```

For explanations of the directives, see:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#response_directives

Fixes #pytorch/pytorch#130571.

Author: edmorley

s3_management/manage.py

@@ -427,7 +427,7 @@ def upload_libtorch_html(self) -> None:
                     key=f"{subdir}/{self.html_name}"
                 ).put(
                     ACL='public-read',
-                    CacheControl='no-cache,no-store,must-revalidate',
+                    CacheControl='max-age=600, public',
                     ContentType='text/html',
                     Body=index_html
                 )
@@ -441,7 +441,7 @@ def upload_pep503_htmls(self) -> None:
                     key=f"{subdir}/index.html"
                 ).put(
                     ACL='public-read',
-                    CacheControl='no-cache,no-store,must-revalidate',
+                    CacheControl='max-age=600, public',
                     ContentType='text/html',
                     Body=index_html
                 )
@@ -454,7 +454,7 @@ def upload_pep503_htmls(self) -> None:
                         key=f"{subdir}/{compat_pkg_name}/index.html"
                     ).put(
                         ACL='public-read',
-                        CacheControl='no-cache,no-store,must-revalidate',
+                        CacheControl='max-age=600, public',
                         ContentType='text/html',
                         Body=index_html
                     )