chore(go): go-openapi requires go.1.20 across the board

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

updated dependencies

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

test(flatten): asserts that the ExpandSpec fix in spec works

This reproduces the $ref issue with relative paths in sibling folders
in responses (same applies to parameters, but not schemas).

Added a test to verify that:
* (i) the invalid path that used to work no longer does
* (ii) the valid path that used not to work now does

* contributes go-swagger/go-swagger#2743

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Fix/ci warnings (#92)

* fix(ci): muted warnings in CI runs due to cache conflicts
* ci: fixed test coverage for sub packages
* tests: added unit tests to the internal packages

This recovers a bit of the loss of test coverage ratio after accounting
for all source files.

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

chore(deps): updated go-openapi deps

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

updated go-openapi dependencies (#87)

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Merge pull request #84 from go-openapi/dev/youyuanwu/bump-deps

upgrade go-openapi dependencies

release v0.21.2

release v0.21.1