fix a Completer's type

[devoncarew]

Fix a strong mode at runtime issue, where a signature was declared to return a Future<Schema>, but at runtime we were returning a Future<dynamic>.

If this looks good, do you mind doing a package publish? This library is consumed by the Flutter command line tool, and a publish would help us make it strong mode clean. Thanks!

[aviary3-wk]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure
• Verify aviary.yaml coverage of security relevant code

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[codecov-io]

Codecov Report

Merging #22 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #22   +/-   ##
=======================================
  Coverage   87.02%   87.02%           
=======================================
  Files           3        3           
  Lines         478      478           
=======================================
  Hits          416      416           
  Misses         62       62

Impacted Files	Coverage Δ
lib/src/json_schema/schema.dart	81.94% <ø> (ø)	⬆️

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