attempt to fix json format error

Author: jfdev001

.github/workflows/test_suite_ubuntu.yml

@@ -46,7 +46,8 @@ jobs:
                   || github.event_name == 'push' && github.ref == 'refs/heads/main' ]]
             then
               # Include GCC 9–13 for PRs to main
-              MATRIX_JSON='{
+              MATRIX_JSON=$(cat <<EOF 
+              {
                 "toolchain": [
                   {"compiler": "gcc", "version": 13},
                   {"compiler": "gcc", "version": 12},
@@ -56,20 +57,27 @@ jobs:
                 ],
                 "std": ["f2008"],
                 "include": [
-                  "toolchain": {"compiler": "gcc", "version": 13},
-                  "std": "f2018"
+                  {"toolchain": {"compiler": "gcc", "version": 13}, "std": "f2018"}
                 ]
-              }'
+              }
+              EOF
+              )
             else
               # Only GCC 13 for everything else
-              MATRIX_JSON='{
+              MATRIX_JSON=$(cat <<EOF
+              {
                 "toolchain": [
                   {"compiler": "gcc", "version": 13}
                 ],
                 "std": ["f2008, f2018"]
-              }'
+              }
+              EOF 
+              )
             fi
+            # Convert json to compact line expected by github action
+            MATRIX_JSON=$(echo "$MATRIX_JSON" | jq -c .)
             echo "matrix=${MATRIX_JSON}" >> $GITHUB_OUTPUT
+
   GNU:
     needs: setup-gnu-matrix 
     # The type of runner that the job will run on