chore(eslint): fixing some eslint warnings (#7382)

.eslintrc.js

lib/datasource/git-submodules/index.ts

lib/datasource/index.ts

lib/datasource/packagist/index.ts

lib/util/cache/repository/index.ts

lib/workers/pr/body/updates-table.ts

lib/workers/pr/changelog/release-notes.ts

lib/workers/pr/changelog/source-github.ts

lib/workers/pr/changelog/source-gitlab.ts

lib/workers/pr/code-owners.spec.ts

lib/workers/repository/process/extract-update.spec.ts

lib/workers/repository/process/extract-update.ts

lib/workers/repository/updates/generate.ts