Update CI, deps and README.md

[github-actions[bot]]

Lines Of Code

Language	Files	Lines	Code	Comments	Blanks	Complexity	Bytes
Go	6	1279 (+1)	960	59 (+1)	260	293	28.7K (-3B)
Markdown	1	186 (-3)	167 (-3)	0	19	0	5.5K (-155B)
YAML	5	356 (+6)	291 (+6)	29	36	0	11.2K (+178B)

[github-actions[bot]]

Unit Test Coverage

total: (statements) 48.9%

Coverage of changed lines

No changes in testable statements.

Coverage diff with base branch

No changes in coverage.

[github-actions[bot]]

Go API Changes

# summary
Inferred base version: v0.2.19
Suggested version: v0.3.0

[codecov[bot]]

Codecov Report

Merging #41 (ac72119) into master (af6d025) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #41   +/-   ##
=======================================
  Coverage   41.05%   41.05%           
=======================================
  Files           5        5           
  Lines        3556     3556           
=======================================
  Hits         1460     1460           
  Misses       1802     1802           
  Partials      294      294           

Flag	Coverage Δ
unittests	41.05% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
openapi3/yaml.go	61.42% <ø> (ø)

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