fix: support unicode in markdown

[killuazhu]

What's in the PR

• Fixes an UnicodeEncodeError when scanning non-ini file (such as markdown) containing unicode.
• Add one more ini test case
• Parametrize ini test cases

Offending File content

# Sample markdown file

[guides](http://localhost/guilds)

Test Unicode in non ini file would not fail on python 2.7.

╭─ diagnose
╰» ssh to server x:22324241234423414

key="ToCynx5Se4e2PtoZxEhW7lUJcOX15c54"

Current error message (fixed after using the PR)

Traceback (most recent call last):
  File "detect_secrets/main.py", line 200, in <module>
    sys.exit(main())
  File "detect_secrets/main.py", line 47, in main
    baseline_dict = _perform_scan(args, plugins)
  File "detect_secrets/main.py", line 146, in _perform_scan
    scan_all_files=args.all_files,
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/core/baseline.py", line 58, in initialize
    output.scan_file(file)
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/core/secrets_collection.py", line 206, in scan_file
    self._extract_secrets_from_file(f, filename_key)
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/core/secrets_collection.py", line 306, in _extract_secrets_from_file
    results.update(plugin.analyze(f, filename))
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/plugins/high_entropy_strings.py", line 68, in analyze
    output = analyze_function(file, filename)
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/plugins/high_entropy_strings.py", line 184, in wrapped
    exclude_lines_regex=self.exclude_lines_regex,
  File "/Users/killua/workspace/ww/whitewater-detect-secrets/detect_secrets/plugins/common/ini_file_parser.py", line 25, in __init__
    self.parser.read_file(file)
  File "/Users/killua/.pyenv/versions/2.7.15/lib/python2.7/site-packages/backports/configparser/__init__.py", line 715, in read_file
    self._read(f, source)
  File "/Users/killua/.pyenv/versions/2.7.15/lib/python2.7/site-packages/backports/configparser/__init__.py", line 1100, in _read
    optname = self.optionxform(optname.rstrip())
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)

[KevinHock]

looks great to me 🚢

[killuazhu]

Hey @KevinHock are we going to create a new release anytime soon?

[KevinHock]

Hi @killuazhu, @domanchi was going to test the basic auth changes internally a little bit before we bumped to 0.12.0. But as soon as he does we will make a new release 👍 :)

[killuazhu]

@KevinHock Once this PR is merged, I have another one to address Unicode issue during the audit process. It would be great if both of these PRs can be merged before we cut a new release.

[KevinHock]

Sounds good to me @killuazhu, looking forward to it.