[ci] xvfb-run if GUI

Author: dannypsnl

.github/workflows/coverage.yml

@@ -42,4 +42,5 @@ jobs:
       - run: raco pkg install --auto
       - run: |
           make test
+          #xvfb-run -a make test
           raco cover -b -f coveralls .

.github/workflows/test.yml

@@ -42,4 +42,6 @@ jobs:
         variant: ${{ matrix.racket-variant }}
         version: ${{ matrix.racket-version }}
     - run: raco pkg install --auto
-    - run: make test
+    - run: |
+        make test
+        #xvfb-run -a make test