Merge pull request #150 from humanmade/fix-nightly-test-run

Update test-nightly.yml to use `dev-main`

.github/workflows/test-nightly.yml

@@ -50,7 +50,7 @@ jobs:
     - name: Install PHP Dependencies
       run: |
         composer install --prefer-dist --no-progress --no-suggest --no-interaction --ignore-platform-reqs
-        composer require --dev --update-with-dependencies --prefer-dist roots/wordpress="dev-nightly" wp-phpunit/wp-phpunit="dev-master"
+        composer require --dev --update-with-dependencies --prefer-dist roots/wordpress="dev-main" wp-phpunit/wp-phpunit="dev-master"
 
     - name: Run the tests
       run: |