improve coverage

[Khabib73]

Improve coverage in literal.py from 95% to 97%.

Added 2 tests case:

• test_value_assignment_dict
• test_value_assignment_unique_tuple

Before:

Name                        Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------------------------
isort/literal.py               64      3     14      1    95%   66, 90, 115

After:

Name                        Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------------------------
isort/literal.py               64      1     14      1    97%   66

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.32%. Comparing base (a0cc97f) to head (cef9dcc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2575      +/-   ##
==========================================
+ Coverage   99.25%   99.32%   +0.06%     
==========================================
  Files          41       41              
  Lines        3108     3108              
  Branches      674      674              
==========================================
+ Hits         3085     3087       +2     
+ Misses         13       11       -2     
  Partials       10       10              

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[Khabib73]

@DanielNoord Hi! Rebased on latest master, CI is green, ready to merge :)

[staticdev]

LGTM, thanks a lot @Khabib73

[Khabib73]

Thanks!