Bump minimum required go version to 1.18 and upgrade deps

What's Changed

• bump golang.org/x/tools to v0.13.0 to fix panic in tests by @alexandear in #17

New Contributors

• @alexandear made their first contribution in #17

Full Changelog: v1.2.0...v2.0.0

Upgrade x/tools

bump golang.org/x/tools to v0.7.0 (#14)

May fix an internal error and will include other bug fixes from x/tools

v1.1.1: drop testify dependency (#10)

go mod download will currently overfetch including test dependencies (see https://github.com/golang/go/issues/41431), so, since we barely use this dependency in our tests, we'll skip it for now

v1.1.0: fix: multiple delcaration in same line (#8)

Author: Zehui <[email protected]>