Pytest-cairo

Some minor fixes and changes for compatibility with cairo-lang==0.8.1.

Introduces helper functions for more complex test scenarios:
- `deploy_contract`
- `set_block_number`
- `set_block_timestamp`
- `set_caller_address`
- `set_contract_address`
- `impersonate` (`set_caller_address` + `set_contract_address`)

Introduces the `raises` attribute for asserting expected exceptions are raised.

**Full Changelog**: https://github.com/TimNooren/pytest-cairo/compare/v0.0.2...v0.0.3

Roll back state changes between tests.

**Full Changelog**: https://github.com/TimNooren/pytest-cairo/compare/v0.0.1...v0.0.2

Pass dummy arguments to contract constructor when deploying contract to run tests.