Clean up dependencies

• Upgrade packages
• Replace deprecated packages
• Remove unused packages

Breaking

• Minimum Nodejs version from 10.12.0 to 10.13.0
• Some upgraded dependencies have major version updates

Full Changelog: v5.0.2...v6.0.1

Minor dependency upgrades

v5.0.2

Upgrade all dependencies

Drop support for Node < 10.12

Please use gulp-zopfli-green@4.0.2 if you need to support NodeJs 8 or 9

Support Node 12

Travis CI building on Node 12

Yarn in version control, upgrade dependencies

This version checks the yarn binary in, adds security auditing and upgrades dependencies.

Gulp v4, update dependencies

Upgrades dependencies, including gulp v4

Breaking change

Drop support for gulp v3. Although it should still work as of writing, you should use gulp-zopfli-green^3 if you don't intend to use gulp v4.

Gulp v4

Upgrade to Gulp v4 and other minor dependencies. Shouldn't be breaking, but temporarily published as beta to be safe.

Minor dependency updates

v3.0.1

Update dev dependencies, reformat test/ with prettier

Migrate from node-zopfli to @gfx/zopfli

Drops Node < 8 support

• Better Node 10 support and cross-platform compatibility
• Also slightly improved and modernized the code

Addresses #7 #8

Support Node 10

Forcing specific graceful-fs version to avoid broken usage of node natives.