Darkened greys when line-numbers enabled

[isabelroses]

Describe the bug
When running a freeze --execute "command" --show-line-numbers the greys appear darker.

To Reproduce
Steps to reproduce the behavior:

1. Run freeze with line numbers freeze --execute "ls" --show-line-numbers
2. Run freeze without line numbers freeze --execute "ls"
3. Compare

Expected behavior
The greys would be the same.

Screenshots

[Delta456]

Spotted in #81