Fix and re-enable IRC notifications

[reedy]

There's a few minor issues

• [x] n (count(php-version)) join/quit cycles
• [x] Blank line message sent with just a trailing space - Filed https://github.com/rectalogic/notify-irc/issues/2
• [x] ${{ github.base_ref }} seems to result in no output
• [x] Output result of build (was %{message} in .travis.yml)

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[19:39:19] <wikimedia-github> wikimedia/composer-merge-plugin#476090360 ( - 6415d88441c6873cb1f6dc5c199a8e638fe23752 reedy): Migrate to GitHub Actions - https://github.com/wikimedia/composer-merge-plugin/actions/runs/476090360
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[19:39:26] <wikimedia-github> wikimedia/composer-merge-plugin#476090360 ( - 6415d88441c6873cb1f6dc5c199a8e638fe23752 reedy): Migrate to GitHub Actions - https://github.com/wikimedia/composer-merge-plugin/actions/runs/476090360
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[19:39:33] <wikimedia-github> wikimedia/composer-merge-plugin#476090360 ( - 6415d88441c6873cb1f6dc5c199a8e638fe23752 reedy): Migrate to GitHub Actions - https://github.com/wikimedia/composer-merge-plugin/actions/runs/476090360
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[19:39:40] <wikimedia-github> wikimedia/composer-merge-plugin#476090360 ( - 6415d88441c6873cb1f6dc5c199a8e638fe23752 reedy): Migrate to GitHub Actions - https://github.com/wikimedia/composer-merge-plugin/actions/runs/476090360
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[reedy]

${{ github.base_ref }} seems to result in no output

https://docs.github.com/en/free-pro-team@latest/actions/reference/context-and-expression-syntax-for-github-actions

For both github.head_ref and github.base_ref

This property is only available when the event that triggers a workflow run is a pull_request.

Looks like github.ref will do what we want

The branch or tag ref that triggered the workflow run. For branches this in the format refs/heads/, and for tags it is refs/tags/.

[reedy]

Seems https://github.com/wikimedia/composer-merge-plugin/commit/d854a2143423b02db54194becc421181eae4cd1a probably fixed the "Blank line message sent with just a trailing space"