Raise more accurate ATHR::RequestBody deserialization errors

[Blacksmoke16]

Context

Resolves #290. This PR relies on the underlying deserialization logic to raise the proper exception type. There doesn't really seem to be directly possible for a URI::Error to be raised, so there are no specs on it, but it's handled in code.

Changelog

• Raise more accurate ATHR::RequestBody deserialization errors

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Before merging, remember to add the athena-framework/athena prefix to the PR number in the PR title

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ork/src/controller/value_resolvers/request_body.cr	71.42%	2 Missing ⚠️

Flag	Coverage Δ
compiled	8.12% <0.00%> (-0.01%)	⬇️
unit	92.77% <71.42%> (-0.03%)	⬇️

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Components	Coverage Δ
clock	98.18% <ø> (ø)
console	92.74% <ø> (ø)
dependency_injection	64.28% <ø> (ø)
dotenv	96.80% <ø> (ø)
event_dispatcher	82.75% <ø> (ø)
framework	94.07% <71.42%> (-0.13%)	⬇️
image_size	95.03% <ø> (ø)
mercure	93.37% <ø> (ø)
negotiation	97.69% <ø> (ø)
routing	92.96% <ø> (ø)
serializer	87.23% <ø> (ø)
spec	93.54% <ø> (ø)
validator	92.37% <ø> (ø)

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