v0.13.0

Features

• add @nullable (#11) #11 (sigoden)

Continuous Integration

• use node 16 and npm (sigoden)

Chores

• update README (sigoden)
• add package-lock.json (sigoden)
• dep: update deps to latest version (sigoden)
• release: version v0.13.0 (sigoden)

Commits

• b2be1a7: fix tests (sigoden)
• 39cd8fd: upgrade dependencies (sigoden)