Skooma in minitest parallel setup

[buszu]

Hey, skooma's coverage fails in parallel setup, at least with minitest.

Multiple processes:

PARALLEL_WORKERS=2 bin/rails test
.....................................................................

Finished in 3.441208s, 20.0511 runs/s, 72.3583 assertions/s.
(...)
OpenAPI schema /project_openapi.yml coverage report: 0 / 2 operations (0.0%) covered.
Uncovered paths:
GET /api/v1/endpoint 200
GET /api/v1/endpoint 401

Single process:

PARALLEL_WORKERS=1 bin/rails test
.....................................................................

Finished in 6.011068s, 11.4788 runs/s, 41.4236 assertions/s.
(...)
OpenAPI schema /project_openapi.yml coverage report: 2 / 2 operations (100.0%) covered.
All paths are covered!

Looks like @covered_paths set is respawned with each process, but I wasn't digging that much into it.