Unit fix

[folkertvanheusden]

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixes | https://github.com/Unitech/pm2/issues/6018
| License       | MIT
| Doc PR        | https://github.com/pm2-hive/pm2-hive.github.io/pulls

This fixes the problem that units are written like "mb", "gb" and so on. This should be "MiB", "GiB", etc.

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