fix(deps): update dependency ts-jest to v26.5.4

mentioned in commit 303445cb

mentioned in merge request html-validate!529 (merged)

mentioned in merge request try-online!65 (merged)

mentioned in merge request stylish!23 (merged)

mentioned in merge request html-validate-vue-webpack-plugin!43 (merged)

mentioned in merge request dgeni-front-matter!42 (merged)

mentioned in merge request cypress-html-validate!64 (merged)

mentioned in merge request eslint-config!42 (merged)

mentioned in merge request html-validate-jest-snapshot!55 (merged)

mentioned in merge request example-plugin!38 (merged)

mentioned in merge request html-validate-vue!93 (merged)

mentioned in merge request html-validate-angular!76 (merged)