Fix Codecov report in checks.yml workflow #1212
Description
It seems that Codecov report does not include all tests in the coverage report. According to coverage run documentation there is a flag to create a report from multiple coverage run commands:
-a, --append Append coverage data to .coverage, otherwise it starts
clean each time.
Currently we are not using this flag and probably reports are created only for the last executed command.
In the scope of this issue can be also some kind of refactoring of pyproject.toml file given that some commands are always unsuccessful e.g. poe test due to missing --contract-dir flag for some tests.