fix: correct codeql warnings

[mdevolde]

fix: correct codeql warnings

Why the pull request was made

To correct some warnings from codeql, about code quality.

See:
https://github.com/jxmorris12/language_tool_python/security/code-scanning/1
https://github.com/jxmorris12/language_tool_python/security/code-scanning/2
https://github.com/jxmorris12/language_tool_python/security/code-scanning/3
https://github.com/jxmorris12/language_tool_python/security/code-scanning/4
https://github.com/jxmorris12/language_tool_python/security/code-scanning/5
https://github.com/jxmorris12/language_tool_python/security/code-scanning/6
https://github.com/jxmorris12/language_tool_python/security/code-scanning/7

Summary of changes

Patched these warns:

• __eq__ not overridden when adding attributes
• Module is imported with 'import' and 'import from'
• Should use a 'with' statement
• Statement has no effect
• Unused global variable

Screenshots (if appropriate):

Not applicable.

How has this been tested?

Applied local tests.

Resources

Not applicable.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update (changes to documentation only)
• Refactor / code style update (non-breaking change that improves code structure or readability)
• Tests / CI improvement (adding or updating tests or CI configuration only)
• Other (please describe):

Checklist

• Followed the project's contributing guidelines.
• Updated any relevant tests.
• Updated any relevant documentation.
• Added comments to your code where necessary.
• Formatted your code, run the linters, checked types and tests.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.48%. Comparing base (80c4c71) to head (dc16d03).

Files with missing lines	Patch %	Lines
src/language_tool_python/download_lt.py	81.81%	2 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #196      +/-   ##
==========================================
- Coverage   80.52%   80.48%   -0.04%     
==========================================
  Files          13       13              
  Lines        1725     1732       +7     
==========================================
+ Hits         1389     1394       +5     
- Misses        336      338       +2     

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