fix: dont include tests in npm package

mentioned in commit 03fb7c4c

mentioned in merge request html-validate-jest-snapshot!32 (merged)

mentioned in merge request html-validate-vue-webpack-plugin!19 (closed)

mentioned in merge request dgeni-front-matter!23 (merged)

mentioned in merge request example-plugin!19 (merged)

mentioned in merge request semantic-release-config!14 (merged)

mentioned in merge request html-validate-vue!67 (merged)

mentioned in merge request html-validate-angular!51 (merged)

mentioned in merge request grunt-html-validate!24 (merged)

mentioned in merge request html-validate-vue-webpack-plugin!21 (closed)

mentioned in merge request html-validate-vue-webpack-plugin!23 (merged)