Codecov

Fixes
- 322 Add Cirrus CI

Dependencies and Misc
- 311 Bump coverage from 5.3 to 5.3.1
- 312 Bump coverage from 5.3.1 to 5.4
- 314 Bump coverage from 5.4 to 5.5
- 320 Upgrade to GitHub-native Dependabot

Fixes
- 305 Added option to disable printing of gcov-out
- 308 Handle exceptions that don't have a returncode

Dependencies and Misc
- 301 Update to Python 3.9

Fixes
- [148](https://github.com/codecov/codecov-python/pull/148) Output elapsed time with S3 upload
- [153](https://github.com/codecov/codecov-python/pull/153) Improve error reporting in the "try_run" function and correctly include original command output in the error message
- [295](https://github.com/codecov/codecov-python/pull/295) Added sleep between upload retries.
- [297](https://github.com/codecov/codecov-python/pull/297) Ignore emacs lisp files
- [298](https://github.com/codecov/codecov-python/pull/298) Fix error try_to_run using | without shell=True (fix #284)

Dependencies and Misc
- [290](https://github.com/codecov/codecov-python/pull/290) Bump coverage from 4.5.4 to 5.2.1
- [291](https://github.com/codecov/codecov-python/pull/291) Update python versions
- [292](https://github.com/codecov/codecov-python/pull/292) Add license scan report and status
- [294](https://github.com/codecov/codecov-python/pull/294) Update README with accurate links
- [296](https://github.com/codecov/codecov-python/pull/296) Bump coverage from 5.2.1 to 5.3

- [289](https://github.com/codecov/codecov-python/pull/289)Remove token restriction as it is changed server-side

- [285](https://github.com/codecov/codecov-python/pull/285)Add support for CODECOV_FLAGS
- [276](https://github.com/codecov/codecov-python/pull/276)Add ability to specify number of upload retries

- [279](https://github.com/codecov/codecov-python/pull/279) Fix pinned coverage version