fix: pluralize issues number

[dipsylala]

Displays '2 issues' rather than '2 issue' if multiple issues have been found by an advisory source.

Pluralize tested against:
https://www.npmjs.com/package/react-scripts
https://pypi.org/project/openpyxl-templates/

Checking for regression issues against the following, which should show singular issues in one of the artifacts.
https://www.npmjs.com/package/react-day-picker
https://www.npmjs.com/package/node-sass
https://pypi.org/project/pydub/

Lint output:

xxxxxxxxxxxxxx:~/Projects/overlay$ npm run lint

> lint
> eslint src tests e2e

yarn test output:

Test Suites: 12 passed, 12 total
Tests:       1 skipped, 193 passed, 194 total
Snapshots:   0 total
Time:        5.022 s
Ran all test suites.
Done in 5.98s.

[baruchiro]

See you in the next PR!!