Prevent multiline matrix payload from causing issues in GitHub workflow output

Signed-off-by: George Steel <[email protected]>

Author: gsteel

.github/workflows/continuous-integration.yml

@@ -25,7 +25,11 @@ jobs:
         # This provides a dedicated "check" to asynchronously test all integration tests within the tests/ directory
         # The project name from the tests/ directory is then re-used within the "qa" job to run the generated "container"
         # within that directory.
-        run: cd tests; echo "matrix=[\"$(ls -d * | tr '\n' ' ' | sed 's/ $//' | sed 's/ /\",\"/g')\"]" >> $GITHUB_OUTPUT
+        run: |
+          cd tests;
+          echo 'matrix<<EOF' >> $GITHUB_OUTPUT
+          echo "[\"$(ls -d * | tr '\n' ' ' | sed 's/ $//' | sed 's/ /\",\"/g')\"]" >> $GITHUB_OUTPUT
+          echo 'EOF' >> $GITHUB_OUTPUT
 
   container:
     name: Prepare docker container