test: fix plugin test suite

[jamesgeorge007]

What kind of change does this PR introduce?
Test update

Did you add tests for your changes?
This PR aims at fixing the failing test suite.

If relevant, did you update the documentation?
N/A

Summary
Fixes failing test suite.

Does this PR introduce a breaking change?
No

Other information
N/A

[codecov]

Codecov Report

Merging #174 (aee4d01) into master (31454ea) will increase coverage by 18.68%.
The diff coverage is 51.28%.

@@             Coverage Diff             @@
##           master     #174       +/-   ##
===========================================
+ Coverage   56.56%   75.25%   +18.68%     
===========================================
  Files           3        3               
  Lines         198      198               
  Branches       37       37               
===========================================
+ Hits          112      149       +37     
+ Misses         69       42       -27     
+ Partials       17        7       -10     

Impacted Files	Coverage Δ
src/plugin.js	55.43% <51.28%> (+40.21%)	⬆️

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[alexander-akait]

Let's keep only webpack v5 compatibility