ci: update GitHub actions workflow

[targos]

• Remove actions/setup-node from lint job

There's already a version of Node.js installed on the action runners so
we do not need to explicitly install another one.

• Add Node.js 14.x to the test matrix

• Remove CI: true from the environment

The variable is already set by GitHub

[richardlau]

* Remove actions/setup-node from lint job

There's already a version of Node.js installed on the action runners so
we do not need to explicitly install another one.

The action also installs problem matchers for eslint which will annotate lint failures and mark them inline in the "Files changed" tab for pull requests.

[codecov-io]

Codecov Report

Merging #805 into master will increase coverage by 0.85%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #805      +/-   ##
==========================================
+ Coverage   95.42%   96.27%   +0.85%     
==========================================
  Files          26       30       +4     
  Lines         875      887      +12     
==========================================
+ Hits          835      854      +19     
+ Misses         40       33       -7     

Impacted Files	Coverage Δ
test/fixtures/omg-i-write-to-tmpdir/test.js	100.00% <100.00%> (ø)
test/fixtures/omg-i-pass-with-scripts/build.js	100.00% <0.00%> (ø)
...ixtures/omg-i-pass-with-install-param/test_args.js	100.00% <0.00%> (ø)
test/fixtures/omg-i-pass-with-scripts/test.js	100.00% <0.00%> (ø)
bin/citgm-all.js	92.00% <0.00%> (+1.00%)	⬆️
bin/citgm.js	100.00% <0.00%> (+2.00%)	⬆️
lib/match-conditions.js	93.61% <0.00%> (+2.12%)	⬆️
lib/spawn.js	100.00% <0.00%> (+30.76%)	⬆️

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[targos]

* Remove actions/setup-node from lint job

There's already a version of Node.js installed on the action runners so
we do not need to explicitly install another one.

The action also installs problem matchers for eslint which will annotate lint failures and mark them inline in the "Files changed" tab for pull requests.

Ok, I'll add it back and use v14.x 👍

[targos]

It looks like the tests do not pass on v14.x. Should we add citgm to citgm ??? 😆

[targos]

There was a bug in our fixtures. I fixed it.
Refs: nodejs/node#31030