Fix GitHub Actions failures and add Ruby 3.3 to CI

[mattbrictson]

My initial GitHub Actions CI workflow that I provided in #357 had mistakes that are currently causing it to fail on the master branch.

This PR fixes those failures. I have tested it on my fork, see: https://github.com/mattbrictson/em-http-request/actions/runs/7411502617

The following problems are now fixed:

• Fixed a - uses typo
• Install libcurl4-openssl-dev dependency so that the curb gem builds
• Set fail-fast: false so that one failing Ruby version in the CI matrix doesn't stop the others from running

I also added Ruby 3.3 to the build matrix. Note that this version currently fails, due to known issues documented in #358.

[MatheusRich]

Once this gets merged, I can rerun #358 to confirm the fix.

[knu]

I think you need to migrate from the archived cookiejar gem to the new cookiejar2 gem.

[lawrence-forooghian]

I tried running the actions from this branch on my fork and all of the jobs are passing. Has cookiejar been fixed upstream?

[MatheusRich]

@lawrence-forooghian yes!

[mattbrictson]

I just triggered CI again and all jobs are now passing in this PR, even Ruby 3.3, thanks to the cookiejar fix upstream.

[igrigorik]

ty sir!