Make the branch from which Watcher is built a release branch

[e-dant]

#1013 Builds a C library from e-dant/watcher at the next branch, a development branch, because the release branch did not have the necessary feature (the C library) at the time.

Today (or, just now, really), version 0.12.0 of that repo was released. The C library is there among the other changes.

Some other options exist which still lift us off the development branch:

• Pin the builds to a specific release
• Use binaries from the release assets instead of building things

But, this is a simple fix, the API very seldom changes, and the build seemed happy in #1013, so just switching up the branches to the (rolling) top of the releases seemed simplest.

[dunglas]

Thanks!