Switch coveralls to official GitHub action instead of third-party tool

[RemyKap]

See: https://github.com/marketplace/actions/coveralls-github-action

Currently uses: https://coveralls-python.readthedocs.io/en/latest/

lnldb/.github/workflows/django-ci.yml

Lines 34 to 50 in e9f7fed

	- name: Upload Coverage
	run: coveralls --service=github
	env:
	GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	COVERALLS_FLAG_NAME: ${{ matrix.python-version }}
	COVERALLS_PARALLEL: true
	coveralls:
	name: Indicate completion to coveralls.io
	needs: build
	runs-on: ubuntu-latest
	steps:
	- name: Finished
	run: |
	pip install --upgrade coveralls
	coveralls --service=github --finish
	env:
	GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}