Change `source.url` in `rockspec` to use `git+https://` instead of `git://` protocol (deprecated by GitHub)

[milesrichardson]

GitHub deprecated usage of git:// (unencrypted Git protocol) on March 15th, 2022, so LuaRocks will fail to install any package including a source.url starting with git://. According to the LuaRocks documentation, the correct syntax for referencing https:// URLs is git+https://.

This PR fixes source.url in the .rockspec file and bumps the version. I checked out the branch from master. I also made a second PR (attempting to) backport the fix to v0.16.x: #271

P.S. If your CI is breaking from luarocks packages using git://, here is a quick fix you can use:

git config --global url.https://github.com/.insteadOf git://github.com/