Update readme badge to use GitHub CI instead of unused Travis

[andrew-demb]

While observing if there are any other mentions for unused Travis I found that it's mentioned here

dataloader/resources/prepublish.sh

Line 7 in 55c33d4

# When Travis CI publishes to NPM, the published files are available in the root

But this script was probably not used at all because for publishing in NPM, it used Github action without prepublish script

dataloader/.github/workflows/release.yml

Lines 8 to 17 in 55c33d4

	jobs:
	release:
	name: Release
	uses: the-guild-org/shared-config/.github/workflows/release-stable.yml@main
	with:
	releaseScript: release
	nodeVersion: 16
	secrets:
	githubToken: ${{ secrets.GITHUB_TOKEN }}
	npmToken: ${{ secrets.NPM_TOKEN }}

Should I drop all mentions about prepublish script?

---

Another observation - another abandoned badge - about code coverage (current badge leads to coveralls, but in workflow codecov is used).

To fix this badge it's needed to copy the link from codecov repo settings https://docs.codecov.com/docs/status-badges

https://app.codecov.io/github/graphql/dataloader/commits?branch=main

Should I drop coveralls badge at all?

[saihaj]

Thank you