Further reduce team review request noise from CODEOWNERS (heroku#1618)

We already request language owner review for various automation and
Dependabot related PRs, to reduce the amount of review request
notification noise sent to the language owner team alias.

This adds the GitHub Actions workflow directory to this list too, so
that Dependabot PRs that bump the Actions versions are treated the
same as the language-specific Dependabot PRs.

GUS-W-18951033.

Author: edmorley

.github/CODEOWNERS

@@ -7,5 +7,6 @@
 # by Dependabot or release automation, to reduce team review request noise.
 CHANGELOG.md @schneems
 Gemfile.lock @schneems
+/.github/workflows/ @schneems
 /changelogs/ @schneems
 /lib/language_pack/version.rb @schneems