chore(eslint): stricter settings (#5375)

.eslintrc.js

lib/config/presets.ts

lib/config/validation.ts

lib/datasource/cargo/index.ts

lib/datasource/cdnjs/index.ts

lib/datasource/docker/index.ts

lib/datasource/github/index.ts

lib/datasource/gitlab/index.ts

lib/datasource/index.ts

lib/datasource/maven/index.ts

lib/datasource/rubygems/get-rubygems-org.ts

lib/datasource/sbt/index.ts

lib/datasource/terraform/index.ts

lib/manager/ansible/extract.ts

lib/manager/ansible/update.ts

lib/manager/bazel/extract.ts

lib/manager/bazel/update.ts

lib/manager/buildkite/extract.ts

lib/manager/buildkite/update.ts

lib/manager/bundler/extract.ts