refactor: Import index in datasource tests (#6542)

lib/datasource/cdnjs/__snapshots__/index.spec.ts.snap

lib/datasource/cdnjs/index.spec.ts

lib/datasource/crate/index.spec.ts

lib/datasource/dart/__snapshots__/index.spec.ts.snap

lib/datasource/dart/index.spec.ts

lib/datasource/galaxy/index.spec.ts

lib/datasource/helm/__snapshots__/index.spec.ts.snap

lib/datasource/helm/index.spec.ts

lib/datasource/helm/index.ts

lib/datasource/hex/__snapshots__/index.spec.ts.snap

lib/datasource/hex/index.spec.ts

lib/datasource/ruby-version/__snapshots__/index.spec.ts.snap

lib/datasource/ruby-version/index.spec.ts