SyncSettingsReborn v4.2.2

This release removes the runtime dependency on the "requests" Package
Control package.

Why: the requests build distributed via Package Control is pinned to
requests 2.15.1 (2017) and cannot import on current Sublime builds running
Python 3.14 (it relies on modules removed in Python 3.10/3.13). Its extra
dependencies are not available in the channel, so there was no way to make
it work.

What changes for you:
- All network calls (gist API, settings downloads, auto-sync) now use a
  small built-in HTTP layer based on the Python standard library. Proxy
  settings and timeouts work as before, and a configured proxy now also
  keeps any HTTP_PROXY/HTTPS_PROXY set in the environment for the other
  scheme.
- No Package Control dependencies are installed for this package anymore.
- A .python-version file (3.8) was added so the plugin runs on the modern
  Python host on Sublime Text 4 builds 4050 and newer.
- Fixed a race that could create two Gists: when no gist id was set (e.g.
  right after Delete then Upload), a manual Upload and a background auto-sync
  could each create a Gist and leave an orphan. Gist creation is now
  single-flight, so the second one updates the Gist the first created.

System requirement: Sublime Text 4 (build 4050 or newer). Sublime Text 3
(which only provides the legacy Python 3.3 host) is no longer supported.

Nothing to configure; your gist id, token, and all other settings are
unchanged.
