Release async API and remove combine based API

[roanutil]

• Replace primary targets with new async versions
• Remove *AsyncBeta targets
• Bump minimum Swift version from 5.3 to 5.5

[codecov]

Codecov Report

Merging #8 (e8269bf) into main (78a253d) will decrease coverage by 1.90%.
The diff coverage is 73.43%.

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
- Coverage   76.42%   74.53%   -1.90%     
==========================================
  Files          50       27      -23     
  Lines        1527      640     -887     
==========================================
- Hits         1167      477     -690     
+ Misses        360      163     -197     

Impacted Files	Coverage Δ
Sources/NetworkService/NetworkService.swift	100.00% <ø> (ø)
Sources/NetworkService/Result+NetworkService.swift	79.41% <ø> (ø)
Sources/NetworkService/TopLevelCodable.swift	0.00% <0.00%> (ø)
Sources/NetworkService/URLRequest+build.swift	100.00% <ø> (ø)
...urces/NetworkServiceTestHelper/CodableOutput.swift	0.00% <ø> (ø)
Sources/NetworkServiceTestHelper/Delay.swift	80.00% <ø> (ø)
...urces/NetworkServiceTestHelper/FailureOutput.swift	0.00% <ø> (ø)
Sources/NetworkServiceTestHelper/MockOutput.swift	42.85% <ø> (ø)
...rces/NetworkServiceTestHelper/RepeatResponse.swift	100.00% <ø> (ø)
...ests/NetworkServiceTests/NetworkServiceTests.swift	43.75% <ø> (ø)
... and 14 more

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