Bump apispec from 6.7.1 to 6.8.0

Bumps [apispec](https://github.com/marshmallow-code/apispec) from 6.7.1 to 6.8.0.
- [Changelog](https://github.com/marshmallow-code/apispec/blob/dev/CHANGELOG.rst)
- [Commits](marshmallow-code/apispec@6.7.1...6.8.0)

---
updated-dependencies:
- dependency-name: apispec
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,4 +1,4 @@
-apispec==6.7.1
+apispec==6.8.0
 bunch==1.0.1
 dicttoxml==1.7.16
 dpath==2.2.0