v0.3 Add upstream and other optimizations

What's Changed

• Load certificate at startup by @rosahaj in #9
• fix: reply with sni-specific certs by @rosahaj in #11
• fix: stop goroutine leaks by ensuring both goroutines exit properly by @huboh in #14

New Contributors

• @huboh made their first contribution in #14

Full Changelog: v0.2...v0.3