Use repr when printing strings

[ItsDrike]

Desired change

• Rule(s): SIM300 (However it likely affects more rules)
• Adjustment: Use repr when printing the strings

Explanation

With an if statement like this:

if "}\n" == line:
    ...

the current version of flake8-simplify prints the }\n string with an actual new line, instead of escaping the special newline character, like doing repr("}\n") would. This looks very weird, and many editors don't support it and only print the first line, which is misleading: