Linter and dependency fixes

* testutil: fixed linter warning when initializing non-CSPRNG
* go: removed dependency to github.com/stretchr/testify

bumped github.com/stretchr/testify to 1.8.3

* bumped github.com/stretchr/testify to v1.8.2

build: use the new build package shared workflow (#16)

build: changed linter to golangci-lint (#15)

Merge pull request #14 from azazeal/go1.19

go1.19

Merge pull request #13 from azazeal/go/1.18

go1.18

Merge pull request #12 from azazeal/matrix-coverage

send matrix info to coveralls

Merge pull request #11 from azazeal/ci/coverage

Cleaner coverage report

Merge pull request #10 from azazeal/fix/readme

fixed readme