- Added `go.test.flags` to `go_test`
- Read environment variable `ANSIBLE_CONTAINER_ENABLED` and override: `container.enabled` variable, if available

### Changed
- Removed unused GO_VERSION arg from ssh-container.
- Using consequent `tee` instead of `>`.
- Changed required ansible version to `>=2.15.0`.
- Changed the url of oapi-codegen to the new location.
- Updated README.md

### Fixed
- Ensure dev-container-* is (re-)build with `nocache` option to ensure an updated container state.