Add tests to TranslationsRepository

[codecov-commenter]

Codecov Report

Merging #445 (20cf952) into main (329cfa1) will increase coverage by 0.53%. The diff coverage is 79.66%.

:exclamation: Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

@@            Coverage Diff             @@
##             main     #445      +/-   ##
==========================================
+ Coverage   84.69%   85.22%   +0.53%     
==========================================
  Files         189      190       +1     
  Lines        6912     6986      +74     
==========================================
+ Hits         5854     5954     +100     
+ Misses       1058     1032      -26     

Impacted Files	Coverage Δ
...es/BatchDownloader/Downloader/NetworkSession.swift	0.00% <ø> (ø)
Sources/TestUtilities/NetworkSessionFake.swift	82.17% <ø> (-1.00%)	:arrow_down:
...ources/TranslationService/TranslationsParser.swift	100.00% <ø> (+100.00%)	:arrow_up:
...es/TranslationService/TranslationsRepository.swift	93.54% <66.66%> (+93.54%)	:arrow_up:
...tionServiceTests/TranslationsRepositoryTests.swift	75.00% <75.00%> (ø)
...urces/BatchDownloader/Network/NetworkManager.swift	88.46% <100.00%> (+0.22%)	:arrow_up:
Sources/TestUtilities/LocalTranslationsFake.swift	100.00% <100.00%> (ø)
...TranslationService/TranslationNetworkManager.swift	100.00% <100.00%> (+100.00%)	:arrow_up:
...sts/BatchDownloaderTests/NetworkManagerTests.swift	100.00% <100.00%> (ø)