Release Actions

This set of reusable GitHub Actions implements a versioned release workflow with the following actions:

rainstormy/release/pr creates a release-triggering pull request in GitHub.
rainstormy/release/tag creates a full semantic version tag in Git.
rainstormy/release/major-tag creates a major-only version tag in Git.
rainstormy/release/github creates a draft GitHub release.
rainstormy/release/npm publishes a package to an npm registry.